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. In a hotel, 60% had vegetarian lunch while 30% had non-vegetarian lunch and 15% had both type of lunch. If 96 people were present, how many did not eat either type of lunch ?

Answer: Option D

Explanation:

\begin{aligned}
n(A) = \left(\frac{60}{100}*96\right) = \frac{288}{5} \\
n(B) = \left(\frac{30}{100}*96\right) = \frac{144}{5} \\
n(A\cap B) = \left(\frac{15}{100}*96\right) = \frac{72}{5} \\
\text{People who have either or both lunch} \\
n(A\cup B) = \frac{288}{5}+\frac{144}{5}-\frac{72}{5} \\
= \frac{360}{5} = 72
\end{aligned}

So People who do no have either lunch were = 96 -72
= 24

2. 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

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

Answer: Option C

Explanation:

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

4. 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}

5. In an election between two candidates, 75 % of the voters cast their votes, out of which 2% of the votes were declared invalid. A candidate got 9261 votes which were 75% of the total valid votes. Find the total number of votes.

16800
15800
16700
15700

Answer: Option A

Explanation:

Let the total number of votes enrolled are x.
Number of votes cast = 75% of x
Valid votes = 98% of 75% of x

Now, as 9261 is the 75% of valid casted votes so,

75% of 98% of 75% of x = 9261 [imporant]

\begin{align}
=> \frac{75 \times 98 \times 75 \times x}{100 \times 100 \times 100} = 9261 \\

=> x = 16800
\end{align}