Q8 of 32 Page 107

The water acidity in a 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 for the third reading that will result in the acidity level being normal.

Given,


First reading = 8.48


Second reading = 8.35


Let the third reading be ‘x’


Now, average pH should be between 8.2 and 8.2


Average pH


Multiplying by 3, we get


⇒ 24.6 < 16.83 + x < 25.5


Subtracting 16.83, we get


⇒ 7.77 < x < 8.67


Hence, third pH reading should be between 7.77 and 8.67


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