Answer and Step-by-step explanation:
90ft = a
55ft = b
50ft = c
Plug into equation.

29.4° is the answer.
The mean = 2,000
s = Sigma ( standard deviation ) = 300
M - 2 s = 2,000- 2 * 300 = 2,000 - 600 = 1,400
M + 2 s = 2,000 + 2 * 300 = 2,000 + 600 = 2,600
Answer.
Useful life of light bulbs within 2 standard deviations of the mean is:
A ) Between 1,400 and 2,600 hours
Just isolate f.. buy getting it alone on one side or the other
Lower case numbers for points