Question Detail

Total number of boys and girls in a school is 150. If the number of boys is x, then girls become x% of the total number of students. The number of boys is

Answer: Option B

Explanation:

Clearly,
x% of 150 = 150 - x [as x is number of boys]

\begin{aligned}
=> x + \frac{x}{100} * 150 = 150 \\

=> \frac{5}{2}x = 150 \\

=> x = 60 \\
\end{aligned}

1. Half of 1 percent written as decimal is

5
0.5
0.05
0.005

Answer: Option D

Explanation:

It will be 1/2(1%) = 1/2(1/100) = 1/200 = 0.005

2. In expressing a length of 81.472 km as nearly as possible with the three significant digits, find the percentage error

0.35%
0.34%
0.034%
0.035%

Answer: Option C

Explanation:

Error = (81.5 - 81.472) = 0.028
Required percentage = \begin{aligned}
\frac{0.028}{81.472} \times 100 = 0.034 %
\end{aligned}

3. 2 is what percent of 50

Answer: Option B

Explanation:

2/50 * 100 = 1/25 * 100 = 4 %

4. What is 15 percent of 34

5.10
4.10
3.10
2.10

Answer: Option A

Explanation:

It will be 15% of 34
= (15/100) * 34 = 5.10

5. Out of 450 students of a school, 325 play football, 175 play cricket and 50 neither play football nor cricket. How many students play both football and cricket ?

Answer: Option B

Explanation:

Students who play cricket, n(A) = 325
Students who play football, n(B) = 175
Total students who play either or both games,
\begin{aligned}
= n(A\cup B) = 450-50 = 400\\
\text{Required Number}, n(A \cap B) \\
= n(A)+n(B)-n(A\cup B) \\
= 325 + 175 - 400 = 100
\end{aligned}