Answer:

Step-by-step explanation:
Isolate the variable by dividing each side by factors that don't contain the variable.
Answer:
(22.12, 27.48)
Step-by-step explanation:
Given : Significance level : 
Sample size : n= 8 , which is a small sample (n<30), so we use t-test.
Critical values using t-distribution: 
Sample mean : 
Standard deviation : 
The confidence interval for population means is given by :-

i.e. 

Hence, the 95% confidence interval, assuming the times are normally distributed.= (22.12, 27.48)
Answer:
d < 27
Step-by-step explanation:
Solve for d by subtracting 8 from both sides. This isolates d:
d + 8 < 35
-8 -8
------- -------
d < 27
Let the amount saved by the brother that has less savings be x, then the savings of the other brother is x + 15.
Since their total savings is 55, then
x + x + 15 = 55
2x + 15 = 55
2x = 55 - 15 = 40
x = 40 / 2 = 20
Therefore, one person saved 20 and the other saved 20 + 15 = 35.