6.
If 20% of a = b, then b% of 20 is the same as:
A. 4% of a B. 5% of a
C. 20% of a D. None of these
Answer & Explanation
Answer: Option A
Explanation:
20% of a = b 20 a = b.
100
b% of 20 = b x 20 = 20 a x 1 x 20 = 4 a = 4% of a.
100 100 100 100
View Answer Workspace Report Discuss in Forum
7.
In a certain school, 20% of students are below 8 years of age. The number of students above 8 years of age is of the number of students of 8 years of age which is 48. What is the total number of students in the school?
A. 72 B. 80
C. 120 D. 150
E. 100
Answer & Explanation
Answer: Option E
Explanation:
Let the number of students be x. Then,
Number of students above 8 years of age = (100 – 20)% of x = 80% of x.
80% of x = 48 + 2 of 48
3
80 x = 80
100
x = 100.
View Answer Workspace Report Discuss in Forum
8.
Two numbers A and B are such that the sum of 5% of A and 4% of B is two-third of the sum of 6% of A and 8% of B. Find the ratio of A : B.
A. 2 : 3 B. 1 : 1
C. 3 : 4 D. 4 : 3
Answer & Explanation
Answer: Option D
Explanation:
5% of A + 4% of B = 2 (6% of A + 8% of B)
3
5 A + 4 B = 2 6 A + 8 B
100 100 3 100 100
1 A + 1 B = 1 A + 4 B
20 25 25 75
1 – 1 A = 4 – 1 B
20 25 75 25
1 A = 1 B
100 75
A = 100 = 4 .
B 75 3
Required ratio = 4 : 3
View Answer Workspace Report Discuss in Forum
9.
A student multiplied a number by 3 instead of 5 .
5 3
What is the percentage error in the calculation?
A. 34% B. 44%
C. 54% D. 64%
Answer & Explanation
Answer: Option D
Explanation:
Let the number be x.
Then, error = 5 x – 3 x = 16 x.
3 5 15
Error% = 16x x 3 x 100 % = 64%.
15 5x
View Answer Workspace Report Discuss in Forum
10.
In an election between two candidates, one got 55% of the total valid votes, 20% of the votes were invalid. If the total number of votes was 7500, the number of valid votes that the other candidate got, was:
A. 2700 B. 2900
C. 3000 D. 3100
Answer & Explanation
Answer: Option A
Explanation:
Number of valid votes = 80% of 7500 = 6000.
Valid votes polled by other candidate = 45% of 6000
= 45 x 6000 = 2700.
100