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# If for the past ‘n’ matches, the average runs scored by Steve is 65 ru

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Joined: 04 Jan 2015
Posts: 1991
If for the past ‘n’ matches, the average runs scored by Steve is 65 ru  [#permalink]

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Updated on: 12 Aug 2018, 23:05
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Difficulty:

25% (medium)

Question Stats:

72% (01:12) correct 28% (01:28) wrong based on 67 sessions

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Solve any Mean and Standard deviation question under a minute- Exercise Question #3

3-If for the past ‘n’ matches, the average runs scored by Steve is 65 runs. If today’s century increased his overall average to 70 runs. What is the value of n?

Options

a) 5
b) 6
c) 7
d) 8
e) 9

To solve question 4: Question 4

To read the article: Solve any Mean and Standard deviation question under a minute

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Originally posted by EgmatQuantExpert on 04 Jul 2018, 06:50.
Last edited by EgmatQuantExpert on 12 Aug 2018, 23:05, edited 2 times in total.
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Re: If for the past ‘n’ matches, the average runs scored by Steve is 65 ru  [#permalink]

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Updated on: 07 Jul 2018, 07:11

Solution

Given:

• Average run scored by Steve in past ‘n’ matches= 65.
• In today’s match, he scored a century.
• New average after he hit the century is 70 runs.

To find:
• The value of n
.

Approach and Working:

Method-1

• $$\frac{Sum\ of\ run\ in\ n\ matches}{n}= 65$$
o Sum of runs in n matches= 65n

• $$\frac{Sum\ of\ runs\ in\ n\ matches+100}{n+1}= 70$$
o 65n+100= 70n+70
o 5n= 50
o n=6

Hence, the correct answer is option B.
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Originally posted by EgmatQuantExpert on 04 Jul 2018, 06:51.
Last edited by EgmatQuantExpert on 07 Jul 2018, 07:11, edited 1 time in total.
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Re: If for the past ‘n’ matches, the average runs scored by Steve is 65 ru  [#permalink]

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04 Jul 2018, 07:42
EgmatQuantExpert wrote:
Solve any Mean and Standard deviation question under a minute- Exercise Question #3

3-If for the past ‘n’ matches, the average runs scored by Steve is 65 runs. If today’s century increased his overall average to 70 runs. What is the value of n?

Options

a) 5
b) 6
c) 7
d) 8
e) 9

$$65n + 100 = 70(n + 1)$$

Or, $$65n + 100 = 70n + 70$$

Or, $$5n = 30$$

Or, n = 6 , Answer must be (B)
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Re: If for the past ‘n’ matches, the average runs scored by Steve is 65 ru  [#permalink]

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04 Jul 2018, 07:53
Equation is one way.
Another way is to think about the the impact 100 had on 65's which increased it to 70.
Since the new average is 70 , the excess score for the last match is 100-70 = 30.
We have 30 runs which we can distribute to the previous matches to bring it up to 70.
Since each score needs to be increased by 5 , we get 30/5 = 6
Re: If for the past ‘n’ matches, the average runs scored by Steve is 65 ru &nbs [#permalink] 04 Jul 2018, 07:53
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