# Average Questions

FACTS  AND  FORMULAE  FOR  AVERAGE QUESTIONS

1. Average =$\inline \fn_cm \left ( \frac{Sum \; of\; observations}{No.of\; observations} \right )$

2. Suppose a man covers a certain distance x kmph and an equal distance at y kmph. Then, the average speed during the whole journey is$\inline \fn_cm \left ( \frac{2xy}{x+y} \right )$Kmph

Q:

A batsman makes a score of 87 runs in the 17th inning and thus increases his average by 3. Find his average after 17th inning?

Let the average after 7th inning = x

Then average after 16th inning = x - 3

$\inline&space;\fn_jvn&space;\therefore$ 16(x-3)+87 = 17x

$\inline&space;\fn_jvn&space;\therefore$  x = 87 - 48 = 39

22740
Q:

The average of runs of a cricket player of 10 innings was 32. How many runs must he make in his next innings so as to increase his average of runs by 4 ?

 A) 76 B) 79 C) 85 D) 87

Explanation:

Average = total runs / no.of innings = 32

So, total = Average x no.of innings = 32 x 10 = 320.

Now increase in avg = 4runs. So, new avg = 32+4 = 36runs

Total runs = new avg x new no. of innings = 36 x 11 = 396

Runs made in the 11th inning = 396 - 320 = 76

43 21390
Q:

The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero ?

 A) 0 B) -1 C) 1 D) none of these

Explanation:

Average of 20 numbers = 0.

$\inline \fn_cm \therefore$Sum of 20 numbers = (0 * 20) = 0.

It is quite possible that 19 of these numbers may be positive and if their sum is a, then 20th number is (- a).

77 21233
Q:

The average weight of 8 persons increases by 2.5 kg when a new person comes in place of one of them weighing 65 kg. What might be the weight of the new person ?

 A) 70 kg B) 75 kg C) 80 kg D) 85 kg

Explanation:

Total weight increased = (8 x 2.5) kg = 20 kg.

Weight of new person = (65 + 20) kg = 85 kg.

46 21083
Q:

The average of five consecutive odd numbers is 61. What is the difference between the highest and lowest numbers :

 A) 4 B) 8 C) 12 D) 16

Explanation:

Let the numbers be x, x + 2, x + 4, x + 6 and x + 8.

Then  [x + (x + 2) + (x + 4) + (x + 6) + (x + 8) ] / 5 = 61.

or 5x + 20 = 305 or x = 57.

So, required difference = (57 + 8) - 57  = 8