Aptitude - Ratio and Proportion
Overview Exercise "We cannot solve our problems with the same thinking we used when we created them."
- Albert Einstein
11.
The salaries A, B, C are in the ratio 2 : 3 : 5. If the increments of 15%, 10% and 20% are allowed respectively in their salaries, then what will be new ratio of their salaries?
A. 3 : 3 : 10 B. 10 : 11 : 20 C. 23 : 33 : 60 D. Cannot be determined
Answer: A
Explanation:
Let A = 2k , B = 3k and C = 5k .
A's new salary =
115
of 2k =
115
x 2k
=
23k
100
100
10
B's new salary =
110
of 3k =
110
x 3k
=
33k
100
100
10
C's new salary =
120
of 5k =
120
x 5k
= 6k
100
100
23k
:
33k
: 6k
= 23 : 33 : 60
10
10
12.
If 40% of a number is equal to two-third of another number, what is the ratio of first number to the second number?
Answer: B
Explanation:
2A
=
2B
5
3
13.
The fourth proportional to 5, 8, 15 is:
Answer: B
Explanation:
Let the fourth proportional to 5, 8, 15 be x .
Then, 5 : 8 : 15 : x
x = (8 x 15)
14.
Two number are in the ratio 3 : 5. If 9 is subtracted from each, the new numbers are in the ratio 12 : 23. The smaller number is:
Answer: B
Explanation:
Let the numbers be 3x and 5x .
Then,
3x - 9
=
12
5x - 9
23
x - 9) = 12(5x - 9)
x = 99
x = 11.
15.
In a bag, there are coins of 25 p, 10 p and 5 p in the ratio of 1 : 2 : 3. If there is Rs. 30 in all, how many 5 p coins are there?
Answer: A
Explanation:
Let the number of 25 p, 10 p and 5 p coins be x , 2x , 3x respectively.
Then, sum of their values = Rs.
25x
+
10 x 2x
+
5 x 3x
= Rs.
60x
100
100
100
100
60x
= 30
x =
30 x 100
= 50.
100
60
Hence, the number of 5 p coins = (3 x 50) = 150.
New ratio
x =