Answer:
a) Mean = 382.3 psi
Standard deviation = 20.8 psi
b) 392.7 psi
c) P(X<400)=0.8026
Step-by-step explanation:
a) The population mean can be estimated as equal to the mean of the sample, and the population standard deviation can be estimated from the sample standard deviation:


b) We start by searching for the z-value for the 95th percentile. This value is
z=1.645:

Then, the strength value below which 95% of all welds will have their strengths is:

c) We calculate the probability of X being equal or less than 400 as:

For this case we have the following expression:
h (t) = -16t ^ 2 + 64t + 80
For t = 0 we have:
h (0) = -16 (0) ^ 2 + 64 (0) + 80
h (0) = -0 + 0 + 80
h (0) = 80 feet
Therefore the number 80 represents the initial height of the rocket
Answer:
the 80 in the expression represented:
the initial height of the rocket
I'm pretty sure that it is 140. Hope I helped!
The answer is B. it is caused by weather change
B. 10^6 = 1,000,000. Close