Average age of boys in a class is 16 years and average age of girls is 15 years, what is the average age of all

Answer: Option B

Explanation:

Average speed will be

$$\begin{aligned} \frac{2xy}{x+y} km/hr = \frac{2(50)(30)}{50+30} km/hr \end{aligned}$$

= 37.5 km/hr

Answer: Option B

Explanation:

As the month begin with sunday, so there will be five sundays in the month. So result will be:
$$\begin{aligned} = (\frac{510 \times 5 + 240 \times 25}{30}) = (\frac{8550}{30}) = 285 \end{aligned}$$

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

Answer: Option B

Explanation:

$$\begin{aligned} \frac{(55 \times 50) +(60 \times 55) +(45 \times 60) }{55 + 60 + 45} \end{aligned}$$

$$\begin{aligned} \frac{8750}{160} = 54.68 \end{aligned}$$

Answer: Option A

Explanation:

$$\begin{aligned} Average = \frac{3(1+2+3+4+5)}{5} = \frac{45}{5} = 9 \end{aligned}$$