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Standard IX

Mathematics

Properties of Measures of Central Tendency

The average h...

Question

The average height of $10$ students in a class is $105 c m s$ . If $20$ more students with an average height of $120 c m s$ join them what will be the average height be?

105 c m s

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110 c m s

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112 c m s

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115 c m s

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Solution

The correct option is D $115 c m s$
Average height of $10$ student $= 105 c m s$
Average height of $20$ student $120 c m s$
Total Average height of $30$ student
$= \frac{10 \times 105 + 20 \times 120}{30}$
$= 115 c m$ .

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The average height of 10 students in a class is 105 cms. If 20 more students with an average height of 120 cms join them what will be the average height be?

The correct option is D 115 cmsAverage height of 10 student =105 cmsAverage height of 20 student 120 cmsTotal Average height of 30 student=10×105+20×12030=115 cm.

The average height of $10$ students in a class is $105 c m s$ . If $20$ more students with an average height of $120 c m s$ join them what will be the average height be?

The correct option is D $115 c m s$
Average height of $10$ student $= 105 c m s$
Average height of $20$ student $120 c m s$
Total Average height of $30$ student
$= \frac{10 \times 105 + 20 \times 120}{30}$
$= 115 c m$ .