FACTS  AND  FORMULAE  FOR  AVERAGE QUESTIONS

 

 

1. Average =

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 isKmph

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


\inline \fn_jvn \therefore 16(x-3)+87 = 17x


\inline \fn_jvn \therefore  x = 87 - 48 = 39

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105 18444
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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73 18300
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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39 16954
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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30 16925
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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38 16888