# 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?

Answer

Let the average after 7th inning = x

Then average after 16th inning = x - 3

16(x-3)+87 = 17x

x = 87 - 48 = 39

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24779
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

Answer & Explanation Answer: A) 76

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

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47 23219
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

Answer & Explanation Answer: D) 85 kg

Explanation:

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

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

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48 22923
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

Answer & Explanation Answer: A) 0

Explanation:

Average of 20 numbers = 0.

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).

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77 22420
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

Answer & Explanation Answer: B) 8

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

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69 21499
Q:

A grocer has a sale of Rs 6435, Rs. 6927, Rs. 6855, Rs. 7230 and Rs. 6562 for 5 consecutive months. How much sale must he have in the sixth month so that he gets an average sale of Rs, 6500 ?

 A) 4991 B) 5467 C) 5987 D) 6453

Answer & Explanation Answer: A) 4991

Explanation:

Total sale for 5 months = Rs. (6435 + 6927 + 6855 + 7230 + 6562) = Rs. 34009.

Required sale = Rs.[(6500 x 6) - 34009]

= Rs. (39000 - 34009)

= Rs.  4991.

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50 21285
Q:

The average of 7 consecutive numbers is 20. The largest of these numbers is :

 A) 21 B) 22 C) 23 D) 24

Answer & Explanation Answer: C) 23

Explanation:

Let the numbers be x, x + 1, x + 2,  x + 3, x + 4, x + 5 and x + 6,

Then   (x + (x + 1) + (x + 2) + (x + 3) + (x + 4) + (x + 5) + (x + 6)) / 7 = 20.

or  7x + 21 = 140 or 7x = 119 or x =17.

Latest number = x + 6 = 23.

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32 17600
Q:

The average weight of a class of 24 students is 35 kg. If the weight of the teacher be included, the average rises by 400 g. The weight of the teacher is :

 A) 45 kg B) 46 kg C) 47 kg D) 48 kg

Answer & Explanation Answer: A) 45 kg

Explanation:

Weight of the teacher = (35.4 x 25 - 35 x 24) kg = 45 kg.

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41 16878