ATENEO DE DAVAO UNIVERSITY

Km. 7 Central Park Blvd, Talomo, 8016 Davao City, Philippines

Tel No. +63 (82) 221.2411 local 6200
E-Mail: shs@addu.edu.ph * www.addu.edu.ph

In Consortium with Ateneo de Zamboanga University and Xavier University

SENIOR HIGH SCHOOL – General Mathematics

Answer Key
General Mathematics
Drill no.7: Simple and Compound Interests

Name: _________________________________ Score: ____________________

Grade & Section: _____________ Track: __________ Date Submitted: ____________

Test I. Complete the Table

Instruction: Complete the unknown value in each table. Show your responses (Round off to the
closest hundredths)
1. Find the unknown principal P, rate r, time t, the interest I, and maturity value by
Accomplishing the table.
Table A
Principal Rate (r) Time (t), in years Simple Interest Maturity or Future
Amount(P) (IS) Value
Php 3000 % (a) 0.5 years Php 41.25 Php 3,041.25

(b) 6.75 % 5 years and 3 Php 85,050 Php 325,050

Php240,00
0 months
Php 1,110,000 (c) 22 years Php 2,258,850 Php 3,368,850
9.25%

Php 590,100 16 years (d) Php 1,274,616

% Php
684,516
Php 900,000 10.32 % 9 years and 4 Php 866,880 (e) Php 1,766,880
months

Solution:
1. c.) 𝑡 = a.) 𝑃 = 𝐹 − 𝐼 𝐼
b.) 𝑟 = 𝑃𝑡
𝐼
2,258,850
𝑃𝑟 41.25 𝑟=
𝑡= 𝑃 = 325050 − 85050 (1,110,000)(22)
(3000)(0.0275)
𝑡 = 0.5 𝑦𝑒𝑎𝑟𝑠 𝑟 = 0.0925 𝑜𝑟 9.25%
𝑃 = 𝑃ℎ𝑝240,000

e.) 𝐼 = 𝑃𝑟𝑡 d.) 𝐹 = 𝑃 +

𝐼
 ATENEO DE DAVAO UNIVERSITY
Km. 7 Central Park Blvd, Talomo, 8016 Davao City, Philippines
Tel No. +63 (82) 221.2411 local 6200
E-Mail: shs@addu.edu.ph * www.addu.edu.ph

In Consortium with Ateneo de Zamboanga University and Xavier University

SENIOR HIGH SCHOOL – General Mathematics

𝐼 = (590,100)(0.0725)(16) 𝐹 = 900,000 + 866,880

𝐼 = 𝑃ℎ𝑝684,516 𝐹 = 𝑃ℎ𝑝1,766,880

Table B
Principal Amount Rate (r) Interest Time (t), in Compound Interest Maturity or
(P) Compounded years (IC) Future Value (Fc)
(a) 3.50% Semi- 5 years and 6 Php 9,461.69 Php 54, 461.69
Php45,000
annually months
Php 75,500 4% Quarterly 7 years Php 24, 257.47 (b) Php99,757.4
7
Php 355,000 6% Monthly 6 years Php 153, 375.72 (c) Php508.375.7
2
Php 600,000 .75 % Semi- 10 years (d) Php 646, 639.78
Php46,639.78
annually
(e) 4.35 % Monthly 8 years and 4 Php 183, 458.58 Php 604,258.58
Php420,80
0 months

Solution:
𝑟 𝑚𝑡
a.) 𝐹 = 𝑃 (1 + 𝑚)

0.035 2(5.5)
54,461.69 = 𝑃 (1 + ) 𝑃 =𝐹−𝐼
2
0.035 2(5.5) 𝑜𝑟 𝑃 = 54,461.69 − 9,461.69
54,461.69 𝑃 (1 + 2 )
=
0.035 2(5.5) 0.035 2(5.5) 𝑃 = 𝑃ℎ𝑝45,000
(1 + 2 ) (1 + 2 )

𝑃 = 𝑃ℎ𝑝45,000
𝑟 𝑚𝑡 𝐹 =𝑃+𝐼
b.) 𝐹 = 𝑃 (1 + 𝑚)

0.04 4(7) 𝑜𝑟
𝐹 = 75,500 (1 + )
4
 ATENEO DE DAVAO UNIVERSITY
Km. 7 Central Park Blvd, Talomo, 8016 Davao City, Philippines
Tel No. +63 (82) 221.2411 local 6200
E-Mail: shs@addu.edu.ph * www.addu.edu.ph

In Consortium with Ateneo de Zamboanga University and Xavier University

SENIOR HIGH SCHOOL – General Mathematics

𝐹 = 75,500 + 24,257.47

𝐹 = 𝑃ℎ𝑝99,757.47 𝐹 = 𝑃ℎ𝑝99,757.47

𝑟 𝑚𝑡
𝑐. ) 𝐹 = 𝑃 (1 + ) 𝑑. ) 𝐼 = 𝐹 − 𝑃 𝑒. ) 𝑃 = 𝐹 − 𝐼
𝑚
0.06 12(6)
𝐹 = 355,000 (1 + ) 𝐼 = 646,639.78 − 600,00 𝑃 = 604,258.58 −183,458.58
12

𝐹 = 𝑃ℎ𝑝508,357.72 𝐼 = 𝑃ℎ𝑝46,636.78 𝑃 = 𝑃ℎ𝑝420,800

Test II: Multiple Choice

Instruction: Read each problem critically and form the right response that best depicts the
problem. (Round off to the nearest hundredths)

1. Lisa put 50,000 Philippine pesos in a speculation account at a simple interest rate of .25%
every year. Dara put 25,000 Philippine pesos in a venture account at a simple interest fee of
10% every year. Who will have acquired more interest following two years?

a. Lisa acquires revenue 10folds as Dara procured.

b. Dara acquires revenue 20folds times as Lisa procured.
c. Lisa acquires revenue 20folds times as Dara procured.
d. Dara acquires revenue 10folds times as Lisa procured.

2. Ryan lent 7,500 Philippine pesos to Louis for a seriously significant time frame and 5,000
to Jhong for a seriously lengthy timespan on simple interest at a comparable interest rate. He
got 4,800 Philippine pesos in all from both as interest. What may be the rate of interest every
year?

a. 8% b. .08 % c. .008 % d. .0008 %

 ATENEO DE DAVAO UNIVERSITY
Km. 7 Central Park Blvd, Talomo, 8016 Davao City, Philippines
Tel No. +63 (82) 221.2411 local 6200
E-Mail: shs@addu.edu.ph * www.addu.edu.ph

In Consortium with Ateneo de Zamboanga University and Xavier University

SENIOR HIGH SCHOOL – General Mathematics

3. Joyce contributed a specific sum at six and one-third percent simple interest each year.
Following five years, the interest she got added up to 950 Philippine pesos. What amount did
she contribute?
a. Php 3000 b. Php 30,000 c. Php 300,000 d. Php 3,000,000

4. Angel deposited 200,000 Philippine pesos in the bank, which gives 5% compounded semi-
annually, and let it stay there for ten years. Find the maturity value and interest.

a. Maturity Value = Php 372,723.29, Interest = Php 172,723.29

b. Maturity Value = Php 327,732.29, Interest = Php 127,732.29
c. Maturity Value = Php 327,723.29, Interest = Php 127, 723.92
d. Maturity Value = Php 327,723.29, Interest = Php 127, 723.29

5. Find the compound amount and interest if Php46,000 is invested at 8% compounded quarterly
for five years and six months.

a. The compound amount is Php 71, 151.06 with an interest of Php 25, 115.06
b. The compound amount is Php 71, 115.06 with an interest of Php 25, 151.06
c. The compound amount is Php 71, 115.06 with an interest of Php 25, 115.06
d. The compound amount is Php 71, 115.06 with an interest of Php 25, 115.60

Test III. Word Problem

Instruction: Read everything beneath cautiously. You should compose your response in the
space given. In your answer, you should express the given, the equation, the most widely
recognized approach to driving the response, and the denouement of the problem. (Round off to
the closest hundredths)

1. You get a student loan with the help of Ateneo de Davao University to pay for your educational
expenses this school year. Find the interest on the loan if you borrowed 30,000 Philippine peso
with a 9.5 % simple interest rate for 1 year.
 ATENEO DE DAVAO UNIVERSITY
Km. 7 Central Park Blvd, Talomo, 8016 Davao City, Philippines
Tel No. +63 (82) 221.2411 local 6200
E-Mail: shs@addu.edu.ph * www.addu.edu.ph

In Consortium with Ateneo de Zamboanga University and Xavier University

SENIOR HIGH SCHOOL – General Mathematics

Given:
𝐼 = 𝑃𝑟𝑡
𝑃 = 𝑃ℎ𝑝30,000 𝐼 = (30,000)(0.095)(1)
𝑟 = 9.5% 𝑜𝑟 0.095 𝐼 = 𝑃ℎ𝑝2,850
𝑡 = 1𝑦𝑒𝑎𝑟

2. The CEO of Gold Investments Corporation aims to accumulate 2 million pesos in 15 years. Find
the principal amount on each investment condition.
Given:
𝐹 = 𝑃ℎ𝑝2,000,000
𝑡 = 15 𝑦𝑒𝑎𝑟𝑠

a. % compounded quarterly
Given: 𝑟 𝑚𝑡
𝐹 = 𝑃 (1 + )
𝑟 = 7.75% 𝑜𝑟 0.0775 𝑚
𝑚=4 0.0775 4(12)
2,000,000 = 𝑃 (1 + )
4
0.0775 4(12)
2,000,000 𝑃 (1 + )
= 4
0.0775 4(12) 0.0775 4(12)
(1 + 4 ) (1 + 4 )

𝑃ℎ𝑝796,157.58 = 𝑃

b. % compounded monthly
Given: 𝑟 𝑚𝑡
𝐹 = 𝑃 (1 + )
𝑟 = 7.75% 𝑜𝑟 0.0775 𝑚
𝑚 = 12 0.0775 12(12)
2,000,000 = 𝑃 (1 + )
12
0.0775 12(12) 𝑃ℎ𝑝791,470.59 = 𝑃
2,000,000 𝑃 (1 + )
= 12
0.0775 12(12) 0.0775 12(12)
(1 + 12 ) (1 + 12 )
 ATENEO DE DAVAO UNIVERSITY
Km. 7 Central Park Blvd, Talomo, 8016 Davao City, Philippines
Tel No. +63 (82) 221.2411 local 6200
E-Mail: shs@addu.edu.ph * www.addu.edu.ph

In Consortium with Ateneo de Zamboanga University and Xavier University

SENIOR HIGH SCHOOL – General Mathematics

c. Which investment will require the smallest principal amount? b

1. Merryll needs to compare the simple interest with compound interest on a 95,000
Philippine peso speculation.
Given:
𝑃 = 𝑃ℎ𝑝95,000

a. Find the simple interest assuming that assets procure 11.75 % simple interest for
five years.
Given:
𝐼 = 𝑃𝑟𝑡
𝑟 = 11.75% 𝑜𝑟 0.1175 𝐼 = (95,000)(0.1175)(5)
𝑡 = 5 𝑦𝑒𝑎𝑟𝑠
𝐼 = 𝑃ℎ𝑝55,812.5

b. Find the interest assuming assets acquire 11.75 % compounded quarterly for five
years.
Given:
𝑟 𝑚𝑡
𝑟 = 11.75% 𝑜𝑟 0.1175 𝐹 = 𝑃 (1 + ) 𝐼𝑐 = 𝐹 − 𝑃
𝑚
𝑡 = 5 𝑦𝑒𝑎𝑟𝑠 0.1175 4(5) 𝐼𝑐 = 169,510.24 − 95,000
𝐹 = 95,000 (1 + )
𝑚=4 4
𝐹 = 𝑃ℎ𝑝169,510.24 𝐼𝑐 = 𝑃ℎ𝑝74,510.24

c. Which is the best venture? Why? b

 ATENEO DE DAVAO UNIVERSITY
Km. 7 Central Park Blvd, Talomo, 8016 Davao City, Philippines
Tel No. +63 (82) 221.2411 local 6200
E-Mail: shs@addu.edu.ph * www.addu.edu.ph

In Consortium with Ateneo de Zamboanga University and Xavier University

SENIOR HIGH SCHOOL – General Mathematics

General Mathematics
Problem Set 2 (Answer Key): Simple and Compound Interests

Name: _________________________________ Score: ____________________

Grade & Section: _____________ Track: __________
Date Submitted: ____________

Instruction: Read each item below carefully. You must write your solution on the space provided.
In your solution you must show the given, the equation, the process of driving the answer and
the conclusion of the problem. (Round off to the nearest hundredths)

1. Your mother invested Php 50,000 in a certain bank with a simple interest rate of 8.5% per
year. How long will your money be doubled? (5pts)
Given:
𝑃 = 𝑃ℎ𝑝50,000 𝐹 = 𝑃(1 + 𝑟𝑡)
𝑟 = 8.5% 𝑜𝑟 0.085 100,000 = 50,000(1 + (0.085)𝑡)
𝐹 = 𝑃ℎ𝑝100,000 100,000 = 50,000 + 4,250𝑡
100,000 − 50,000 = 4,250𝑡
50,000 4,250𝑡
=
4,250 4,250
11.76 𝑦𝑒𝑎𝑟𝑠
=𝑡

2. At what simple interest rate will your Php15,000 earn a Php5,000 in 10 years? (5pts)
Given: 𝐼 = 𝑃𝑟𝑡
𝑃 = 𝑃ℎ𝑝15,000 5000 = 15000(10)𝑟
𝐼 = 𝑃ℎ𝑝5,000 5000 150,000𝑟
=
𝑡 = 10 𝑦𝑒𝑎𝑟𝑠 150,000 150,000
3.33% = 𝑟
 ATENEO DE DAVAO UNIVERSITY
Km. 7 Central Park Blvd, Talomo, 8016 Davao City, Philippines
Tel No. +63 (82) 221.2411 local 6200
E-Mail: shs@addu.edu.ph * www.addu.edu.ph

In Consortium with Ateneo de Zamboanga University and Xavier University

SENIOR HIGH SCHOOL – General Mathematics

3. How much will you borrow if you would like to pay Php 25,000 at the end of 2 years
compounded at a rate of
3.7% compounded monthly? (5 pts.)

Given: 𝑟 𝑚𝑡
𝐹 = 𝑃 (1 + )
𝐹 = 𝑃ℎ𝑝25,000 𝑚
𝑡 = 2 𝑦𝑒𝑎𝑟𝑠 0.037 12(2)
25,000 = 𝑃 (1 + )
𝑟 = 3.7% 𝑜𝑟 0.037 12
𝑚 = 12 0.037 12(2)
25,000 𝑃 (1 + 12 )
=
0.037 12(2) 0.037 12(2)
(1 + 12 ) (1 + 12 )

𝑃ℎ𝑝23,219.44 = 𝑃
4. Your first month salary is P18,000 and you plan to save the half of it in a certain bank for 10
years. You consider two banks. Which bank will you choose? Why? Use a mathematical
reasoning to justify your answer. (10pts.)

Given:
𝑃 = 𝑃ℎ𝑝9,000 𝑡 = 10 𝑦𝑒𝑎𝑟𝑠
Bank 1: BDO Optimum Saving Account offers 0.25% simple interest rate.
𝑟 = 0.0025 𝐹 = 𝑃(1 + 𝑟𝑡)
𝐹 = 9,000(1 + (0.0025(10))

𝐹 = 𝑃ℎ𝑝9,225

Bank 2: PNB Debit Savings Account offers 0.100% interest rate, compounded yearly
𝑟 = 0.001 𝑟 𝑚𝑡
𝑚=1 𝐹 = 𝑃 (1 + )
𝑚

0.001 1(10)
𝐹 = 9,000 (1 + )
1

𝐹 = 𝑃ℎ𝑝9,090
 ATENEO DE DAVAO UNIVERSITY
Km. 7 Central Park Blvd, Talomo, 8016 Davao City, Philippines
Tel No. +63 (82) 221.2411 local 6200
E-Mail: shs@addu.edu.ph * www.addu.edu.ph

In Consortium with Ateneo de Zamboanga University and Xavier University

SENIOR HIGH SCHOOL – General Mathematics

Bank 1 is better since it provides higher interest rate, hence it would result to a higher
interest.