Answer:
The probability that it would take more than four hours to construct a soapbox derby car = 0.1587 or 15.87
Step-by-step explanation:
Given -
Mean
= 3 hours
Standard deviation
= 1 hours
Let X be the no of hours to construct a soapbox derby car
the probability that it would take more than four hours to construct a soapbox derby car =
= 
=
Put 
= 1 -
= 1 - .8413 Using z table
= 0.1587
I hope this helps you
1)
f (2)=2.2^2-3.2-7
f (2)=8-6-7
f (2)= -5
2)
f (2)=2.2^2-3.2+7
f (2)=8-6+7
f (2)=9
350000 = 270000(1.05)^n
1.05)^n = 350000/270000 = 1.296296
n = log 1.296296 / log 1.05 = 5.3 years answer