Question Detail

The average age of the mother and her six children is 12 years which is reduced by 5 years if the age of the mother is excluded. How old is the mother

Answer: Option C

1. Reeya obtained 65, 67, 76, 82 and 85 out of 100 in different subjects, What will be the average.

Answer: Option B

Explanation:

$\begin{aligned} ( \frac {65+67+76+82+85}{5} ) = 75 \end{aligned}$

2. The average of four consecutive odd numbers is 24. Find the largest number.

Answer: Option B

Explanation:

Let the numbers are x, x+2, x+4, x+6, then
$\begin{aligned} => \frac{x+(x+2)+(x+4)+(x+6)}{4} = 24 \end{aligned}$

$\begin{aligned} => \frac{4x+12)}{4} = 24 \end{aligned}$

$\begin{aligned} => x+3 = 24 => x = 21 \end{aligned}$

So largest number is 21 + 6 = 27

3. Find the average of first 10 multiples of 7

35.5
37.5
38.5
40.5

Answer: Option C

Explanation:

$\begin{aligned} = \frac {7(1+2+3+...+10)}{10} \end{aligned}$

$\begin{aligned} = \frac {7(10(10+1))}{10 \times 2} \end{aligned}$

$\begin{aligned} = \frac {7(110)}{10 \times 2} = 38.5 \end{aligned}$