# Percentages Quiz Set 010

### Question 1

If 70% of X is Y, then Y% of 70 is?

A

49 % of X.

B

59 % of X.

C

39 % of X.

D

69 % of X.

Soln.
Ans: a

We have Y = \$(70 × X)/100\$, so Y% of 70 is same as \$(70 × X)/100\$% × 70, which can be rearranged to \$(70 × 70)/100\$% × X = 49% of X.

### Question 2

A carton contains 6000 led bulbs, some of them are red, some green and others are blue. How many are green if 9% are red and 3% are blue?

A

5280.

B

5380.

C

5180.

D

5480.

Soln.
Ans: a

The percentage of green is 100 - (9 + 3) = 88. So number of green bulbs = \$88/100\$ × 6000 = 5280.

### Question 3

Mr. X who spends 69% of his salary is able to save Rs. 186. What is his salary?

A

Rs. 600.

B

Rs. 700.

C

Rs. 500.

D

Rs. 800.

Soln.
Ans: a

Let the salary be x. His saving% is 100 - 69 = 31, so 31% of x = 186, which gives x = \$186/31\$ × 100 = Rs. 600.

### Question 4

In a sample there are 1620 items having a value of 50°C. 10% values are below 50°C, and the number of values above 50°C is \$2/3\$ of the items having a value of 50°C. What is the size of the sample?

A

3000 items.

B

3010 items.

C

2990 items.

D

3020 items.

Soln.
Ans: a

The %age ≥ 50°C = (100 - 10) = 90. If x is the size of the sample, 90% of x = 1620 + \$2/3 × 1620\$ = \${5 × 1620}/3\$, which is same as \${90 × x}/100\$ = \${5 × 1620}/3\$. Solving, we get x = 3000.

### Question 5

A clerk multiplied a number by 5/2 instead of 2/5. What is the percentage of error?

A

84 %.

B

86 %.

C

82 %.

D

88 %.

Soln.
Ans: a

If the actual figure is x, the error is \${5x}/2\$ - \${2x}/5\$ = \${5^2x - 2^2x}/{5 × 2}\$ = \${21x}/10\$, so %-error = \${(21x)/10}/{(5x)/2}\$ × 100 = \${21 × 2}/{10 × 5}\$ × 100 = 84%. 