Question

The acidity in a swimming pool is considered

normal if the average of three pH readings, p, is
defined such that 7.0

readings are 7.2 and 7.6, which value for the third
reading will result in an overall rating of normal?
1) 6.2
2) 7.3
3) 8.6
4) 8.8

Answer 1

6.2

Explanation:

`(7.2 + 7.6 + x)/(3) = 7.0 \\ (14.8 + x)/(3) = 7.0 \\ 14.8 + x = 21 \\ x = 21 - 14.8 \\ x = 6.2`