30% decrease
175 divided by 250 = 0.7
1 - 0.7 = 0.3
0.3 = 30%
Answer: The mean of the frequency distribution is 51.7°.
The computed mean 51.7° is greater than the actual mean 50.7° .
Step-by-step explanation:
The given table :
Low Temperature (°F) Frequency Mid -value
Class interval f x fx
40-44 2 42.5 85
45-49 7 47.5 95
50-54 9 52.5 105
55-59 5 57.5 115
60-64 1 62.5 25

The computed mean 51.7° is greater than the actual mean 50.7° .
(x - 9)(x + 9) is your answer. This is called a difference of two squares.