Question

I need help trying to figure this out I think I have and answer but I want to make sure.

Answer 1

34

Explanation:

The mean is calculated as

mean =
`(frequency(midpoint))/(frequency)`

let x be the missing frequency, then

Total frequency × midpoint

= (16 × 2) + 7x + (20 × 12) + (10 × 17) = 32 + 7x + 240 + 170 = 442 + 7x

Total frequency = 16 + x + 20 + 10 = 46 + x, thus

`(242+7x)/(46+x)` = 8.5 ( cross- multiply )

442 + 7x = 8.5(46 + x)

442 + 7x = 391 + 8.5x ( subtract 8.5x from both sides )

442 - 1.5x = 391 ( subtract 442 from both sides )

- 1.5x = - 51 ( divide both sides by - 1.5 )

x = 34

The missing frequency is 34