Answer: 
Step-by-step explanation:
As per given , we have
n = 11

Since population standard deviation is missing, so we use t-test.
Critical t-value for 99% confidence :
[using two-tailed t-value table]
Confidence interval :

Hence, 99% confidence interval for the mean amount of time that students spend in the shower each day.= 
Answer:
1A, 2C, 3X, 4A, 5B, 6W, 7X
Step-by-step explanation:
Im not sure about these answers, can you have the same letter for a different number?
the answers are B,D and F
For first pound it is = $2.41
For next six, = 0.41 * 6 = $2.46
Remaining = 7.99 - (2.41 + 2.46) = 7.99 - 4.87 = 3.12
Now, additional pounds = 3.12 / 0.39 = 8
Total weight = 1 + 6 + 8 = 15
In short, Your Answer would be 15 pounds
Hope this helps!