Let x stand for the length of an individual screw. 100 screws were sampled at a time. The population mean is 2.5 inches and the population standard deviation is 0.2 inches. What is the mean of the sampling distribution of sample means? a) 0.2
b) 2.5
c) 0.02
d) 2.

The  correct option is   b

Step-by-step explanation:

From the question we are told that

   The  sample size is  

    The  population  mean is  

   The  sample  standard deviation is  

Generally the mean of the sampling distribution of sample means is mathematically represented as

=>    

step-by-step explanation:

the original amount doesn't ''re just looking for the time it takes for 1/2 of the substance to we have

(1/2) =)     take the ln   of both sides

ln (1/2)   = )   and we can write

ln(1/2) = ) lne     and lne   = 1     so we have

ln(1/2) = -.1092t     divide both sides by -.1092

t = ln(1/2)/-.1092 = about 6.347 days = about 6.3 days (rounded)

the answer is:

mean: 6

mad: 2.14