2. A motorist travel to a place 150 km away at an avearge speed of 50 km/hr and returns ar 30 km/hr.His average speed for the whole jouney in km/hr is
36.5 km/hr
37.5 km/hr
35.5 km/hr
34.5 km/hr
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
3. Average of first five multiples of 3 is
9
11
13
15
Answer: Option A
Explanation:
\begin{aligned}
Average = \frac{3(1+2+3+4+5)}{5} = \frac{45}{5} = 9
\end{aligned}
4. The average age of husband, wife and their child 3 years ago was 27 years and that of wife and the child 5 years ago was 20 years. The present age of the husband is
40
35
45
55
Answer: Option A
Explanation:
Sum of the present ages of husband, wife and child = (27 * 3 + 3 * 3) years = 90 years.
Sum of the present ages of wife and child = (20 * 2 + 5 * 2) years = 50 years.
Husband's present age = (90 - 50) years = 40 years
5. Reeya obtained 65, 67, 76, 82 and 85 out of 100 in different subjects, What will be the average.