Question Detail

If a - b = 3 and \begin{aligned} a^2 + b^2 = 29 \end{aligned}, then find the value of ab

Answer: Option C

Explanation:

Remember the formula, if not then cram it :)
\begin{aligned} 2ab = (a^2 + b^2)- (a-b)^2 \end{aligned}
=> 2ab = 29 - 9 = 20
=> ab = 10

1. 7500 + (1250 / 50)

7500
7525
7550
8000

Answer: Option B

Explanation:

As per BODMAS rule first we will solve the terms in the bracket then other.
= 7500 + (25) = 7525

2. 18800 / 470 / 20

Answer: Option B

Explanation:

18800 / 470 / 20 = (18800 / 470) / 20 = 40 / 20 = 2

3. Simplify
\begin{aligned} 1+\frac{1}{2}+\frac{1}{4}+\frac{1}{7}+\frac{1}{14}+\frac{1}{28} = ? \end{aligned}

Answer: Option A

Explanation:

By taking LCM we get
=\begin{aligned} \frac{28+14+7+4+2+1}{28}
= \frac{56}{28} = 2\end{aligned}

4. 100 + 50 * 2 = ?

Answer: Option A

Explanation:

After applying BOMAS rule,
First Multiplication will be done then addition
So it will be 100 + 100 = 200

5. In a class free notebooks were distributed among all the children. Each child got notebooks which were one-eighth of the number of children. If number of children been half, then each child would have recieved 16 notebooks in total. Find the total number of books distributed.

Answer: Option B

Explanation:

Let suppose total number of students in class are X.
Then from the question we can conclude it that,
\begin{aligned}
X*\frac{1}{8}X = \frac{X}{2}*16 \\
=> X = 64\\
\text{Total notebooks,} \\
= \frac{1}{8}X^2 \\
= \left( \frac{1}{8} * 64 * 64 \right) \\
= 512
\end{aligned}