Answer:
21
Step-by-step explanation:
2(2) +7
14+7
21
Answer: B, the index fossils in the area of the bones.
(I do need 1 more brainliest to rank up, so if my answer is correct, that would be great, sorry if I sound rude.)
B would be your best answer looking at the graphic chart
Answer:
a) 
With:


b) 

c) 

d) 


Step-by-step explanation:
For this case we know the following propoertis for the random variable X

We select a sample size of n = 81
Part a
Since the sample size is large enough we can use the central limit distribution and the distribution for the sampel mean on this case would be:

With:


Part b
We want this probability:

We can use the z score formula given by:

And if we find the z score for 89 we got:


Part c

We can use the z score formula given by:

And if we find the z score for 75.65 we got:


Part d
We want this probability:

We find the z scores:


