Question Detail

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

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. If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, then the average marks of all the students is

54.48
54.68
54.60
54.58

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}

3. Average of 10 matches is 32, How many runs one should should score to increase his average by 4 runs.

Answer: Option B

Explanation:

Average after 11 innings should be 36

So, Required score = (11 * 36) - (10 * 32)
= 396 - 320 = 76

4. A library has an average of 510 visitors on Sundays and 240 on other day. The average number of visitors in a month of 30 days starting with sunday is

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}

5. 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