Step-by-step explanation:
his father's age= 4x
his mother's age= 4x- 7
his age= x
x+4x+4x-7=101
x+ 4x+ 4x= 101+ 7
9x= 108
= 
x= 12
Tesfa is 12 years old
Answer: search it and i cant see well so sorry
Step-by-step explanation: research
Number 8? I don't know which one you are talking about.
Answer: (0.8115, 0.8645)
Step-by-step explanation:
Let p be the proportion of people who leave one space after a period.
Given: Sample size : n= 525
Number of people responded that they leave one space. =440
i.e. sample proportion: 
z-score for 90% confidence level : 1.645
Formula to find the confidence interval :


Hence, a 90% confidence interval for the proportion of people who leave one space after a period: (0.8115, 0.8645)
The answer is B. h=<span>V<span>2π<span>r<span>2</span></span></span></span>