Question Detail

How many litres of pure acid are there in 8 litres of a 20% solution

Answer: Option B

Explanation:

Question of this type looks a bit typical, but it is too simple, as below...

It will be 8 * 20/100 = 1.6

1. What will be the fraction of 4%

1/20
1/50
1/75
1/25

Answer: Option D

Explanation:

4*1/100 = 1/25.

Friends I know it is quite simple, but trust me while solving percentage questions in Hurry we use to do these types of mistake only. So I recommend you to have a bit practise of this.

2. An inspector rejects 0.08% of the meters as defective, How many meters he examine to reject 2 meteres

1200
2400
1400
2500

Answer: Option D

Explanation:

It means that 0.08% of x = 2
\begin{aligned}
=> ( \frac{8}{100 \times 100} \times x) = 2 \\
=> x = \frac{2 \times 100 \times 100}{8} \\
=> x = 2500
\end{aligned}

3. 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}

4. If x% of y is 100 and y% of z is 200, then find the relation between x and z.

z = x
2z = x
z = 2x
None of above

Answer: Option C

Explanation:

It is , y% of z = 2(x% of y)
=> yz/100 = 2xy/100
=> z = 2x

5. Evaluate 28% of 450 + 45% of 280

Answer: Option C

Explanation:

= (28/100) * 450 + (45/100) * 280
= 126 + 126 = 252