Question

The water acidity in pool is considered normal when the average $pH$ reading of three daily measurements is between $8.2$ and $8.5$. If the first two $pH$ readings are $8.48$ and $8.35$, find the range of $pH$ value of the third reading that will result in the acidity level being normal.

Answer 1

Given data :

First $pH$ value $=8.48$

and second $pH$ value $=8.35$

Let third $pH$ value $=x$

$\because$ It is given that average $pH$ value lies between $8.2$ and $8.5$

$\Rightarrow 8.2<\frac{8.48+8.35+x}{3}<8.5$

$\Rightarrow 24.6<16.83+x<25.5$

$\Rightarrow 7.77<x<8.67$

Hence, the third $pH$ value lies between $7.77$ and $8.67$.