The water acidity in a pool is considered normal

According to the question,

First reading = 8.48

Second reading = 8.35

Now, let the third reading be ‘x’

Average pH should be between 8.2 and 8.5

Average pH = (8.48 + 8.35 + x)/3

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

Multiplying each term by 3, we get

⇒ 24.6 < 16.83 + x < 25.5

Subtracting 16.83 from each term, we get

⇒ 7.77 < x < 8.67

Therefore, from the above equation,

We get that,

The third pH reading should be between 7.77 and 8.67