Ch4 Percentage

1. At what rate p.a. simple interest will
$7 200 amount to $9 600 in 2
A.
B.
C.
D.
E.

1
years?
2

6%
1
6 %
2
10%
1
13 %
3
15%

2. If $2 400 amounts to $2 520 in 15 months by simple interest, what will it amount
to in 2 years at the same interest rate?
A. $2 576
B. $2 592
C. $2 712
D. $2 750
E. $2 862
3. The value of a car depreciates by 15% every year. If its value is $40 000 now,
what was its value 3 years ago correct to the nearest dollar?
A.
B.
C.
D.
E.

$65
$60
$58
$26
$24

133
835
000
300
565

4. John buys a car for $150 000. After 2 years, the value of his car is $121 500. At
what percentage does the car depreciate each year?
A.
B.
C.
D.
E.

8.1%
9%
10%
11%
19%

5. When a number y is increased by 25%, it becomes 100. The number y is given by
A.
B.
C.
D.
E.

100
100
100
100
100







(1 – 25%).
(1 + 25%).
25%.
(1 + 25%).
(1 – 25%).

6. If k% of $30 is $ 0.3, the value of k is
A.
B.
C.
D.
E.

0.01.
0.09.
1.
9.
10.

7. Given A  80 and B  100. Which of the following is true?
A.
B.
C.
D.
E.

A is smaller than B by 25%.
A is greater than B by 25%.
B is smaller than A by 25%.
B is greater than A by 25%.
None of the above.

8. What is the simple interest on $2 400 at 4% p.a. for 2 years?
A.
B.
C.
D.
E.

$96
$192
$480
$2 592
$19 200

9. In each month, a man pays one-third his salary for his rent and saves 25% of the
rest. We know that he saves $4 000 each month. Find his salary and the rent in
each month.

10. A camera which costs $2 000 is marked at a profit of 40%.
(a) Find the marked price of the camera.
(b) If the camera is sold at a discount of 10%, what is the profit %?

11. A man deposits $6 000 in a bank at 10% p.a. for 3 years. Find the
(a) simple interest,
(b) total amount of money he has.

12. (a) What is 36% of 900?
(b) What percentage of 900 is 36?
(c) 36% of x is 900. Find the value of x.
(14 marks)

13. Find the quantity obtained when
(a) $450 is increased by 26%;
(b) 720g is decreased by 15%.
(14 marks)

14. Express the following as percentages.
(a) 0.125
(c)

7
50

(b) 4.06
(d)

18
25

15.
In an 800g tin of Cream of Mushroom soup, there is 6.2g of protein, 20.7g
of fat, 34g of carbohydrate, 0.4g of sugars, 3.43g of sodium and 150 mg of
potassium.
Find the percentage in the tin (correct to 2 decimal places of a per cent) of:
(a) Carbohydrate
(b) fat
(c) Sugars

1. (D)

9.

2. (B) 3. (A) 4. (C) 5. (D) 6. (C) 7. (D) 8. (B)

Let $x be the monthly salary of the man.

1
Then (1  )x  25%  4 000
3
2
25
x
 4 000
3
100
1
x  4 000
6
1
x  6  4 000  6
6
x  24 000
1
The monthly rent = $(  24 000)
3
= $8 000


His monthly salary is $24 000 and the monthly
rent is $8 000.

10. (a)

The profit = $(2 000  40%)
40
= $(2 000 
)
100
= $800

 The marked price=$(2 0 0+80 )
=$2 80
(b)

The selling price = $[2 800  (100%  10%)]
= $[2 800  90%]
90 

= $  2 800 

100


 $2 520
The profit = $(2 520  2000)
 $520
$520
 100%
$2 000
 26%

Profit % =

11

(a) The simple interest

 6 000  10  3 



100
 $1 800
 $

(b) The amount

 $(6 000 + 1 800)
= $7 800

12. (a)
36% of 900 = 36%  900
36
=
 900
100
 324

(b)
36
 100%
900
 4%

The percentage =

(c)

36%  x  900
36
 x  900
100
36
36
36
x
 900 
100
100
100
100
x  900 
36
 2 500

13.(a) The new quantity
= $[450  (100% + 26%)]
= $[450  126%]
126
= $[450 
]
100
 $567
(b) The new quantity
= [720  (100%  15%)] g
= [720  85%] g
85
= [720 
]g
100
 612 g

14. (a) 0.125  12.5%
(b) 4.06  406%
(c)
7
7

 100%
50 50
 14%
(d)

18 18

 100%
25 25
 72%

15. (a) 4.25%

(b) 2.59%

(c) 0.05%