Answer:
epic
Step-by-step explanation:
epic
Given:
Sample mean = 65.4
Standard deviation = 1.2
Sample size = 45
Confidence level = 99%
To find:
The confidence interval.
Solution:
The formula for confidence interval is

where,
is sample mean, z* is confidence value, s is standard deviation and n is sample size.
Confidence value or z-value at 99% = 2.58
Putting the given in the above formula, we get




Therefore, the correct option is D.
Answer:
Step-by-step explanation:
we can write -9 instead of x and y=1 instead of 1
so we write solution again
-9a+1b=-31
-9a-1b=-41
-18a=-72
a=4
we should write 4 instead of a
-9(4)+1b=-31
-36+b=-31
b=5
a=4