I’m pretty sure it’s 86, because you need to subtract 2 from the first side then you have 86 = X
Answer:
7.0 < x < 7.6
X is the ideal pH of the swimming pool
Alright, so let's make both 7/8 and 3/10 into fractions with the same denominator.
The lowest common denominator for both of these is 80.
So, we multiply the top and bottom of 7/8 by 10, and the top and bottom of 3/10 by 8 to get fractions we can compare.
So, we have 70/80 of a candy bar, and we want to make servings of 24/80 each.
How many times can 24 go into 70? 2 times, with a remainder of 22.
So, Tony can make 2 servings.
Let

denote the number of minutes spent brushing his teeth, and let

be the mean and

the standard deviation for this distribution.

The z-score corresponding to this probability is approximately

, which means

Next, (note the sign change)

The corresponding z-score is approximately

, so you have

Solving the two equations for

and

, you'll find that the mean is approximately

and the standard deviation is approximately

.