Candidates of Four Schools Appear in a Mathematics Test. the Data Were as Follows:Schools No. of Candidates Average Scoreif the Average Score of the Candidates of All the Four Schools is 66, Find the - Mathematics

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Candidates of four schools appear in a mathematics test. The data were as follows:

Schools  No. of candidates

Average score

1 60 75
2 48 80
3 N A 55
4 40 50

If the average score of the candidates of all the four schools is 66, find the number of
candidates that appeared from school 3.

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Solution

Let no. of candidates appeared from school 3 = x.

Schools  No.of candidates

Average score

1 60 75
2 48 80
3 x 55
4 40 50

Given, average score of all school = 66.

⇒ `(N_1barx_1 +N_2barx_2 + N_3barx_3 + N_4barx_4 )/(N_1 +N_2 + N_3 + N _4) = 66`

⇒ `(60+ 75 + 48 +80 + x xx 55 +40 xx 50)/(60 + 48 + x +40)= 66`

⇒`(4500 + 3840 + 55x + 2000)/148 + x`

⇒`(10340 + 55x)/(148 + x) = 66`

⇒ 10340 + 55x = 66x + 9768 

⇒ 10340 + 9768 = 66x - 55x

⇒ 11x = 572

⇒ `x = 572/11`= 52

∴ No. of candidates appeared from school (3) – 52.

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Chapter 24: Measures of Central Tendency - Exercise 24.2 [Page 15]

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RD Sharma Mathematics for Class 9
Chapter 24 Measures of Central Tendency
Exercise 24.2 | Q 11 | Page 15

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