## Solution
3 hours at a speed of 20 miles per hour gives us Distance = 20*3 = 60 miles
6 hours at a speed of 30 miles per hour gives us Distance = 30*6 = 180 miles
1 more hour at 40 miles per hour gives us Distance = 40*1 = 40 miles
Total Distance = 60+180+40 = 280 miles
Total Time = 3+6+1 = 10 Hours
Average Speed = 280 / 10 = 28 Miles per hour
## What the question and answer could be
Joel sailed for 3 hours at a speed of 20 miles per hour, then for 6 hours at 30 miles per hour and finally, 1 more hour at 40 miles per hour. What was the average speed of Joel during the whole sail?
.
Options:
(A) 25
(B) 27.5
(C) 28
(D) 30
(E) 32
(C)

## Solution
1 to 9 = 9 * 9 = 81
1 to 5 = 5 * 10 = 50
5 to 9 = 5 * 8 = 40
5th = 50 + 40 = 90 – 81 = 9
## What the question and answer could be
The average of 9 observations was 9, that of the 1st of 5 being 10 and that of the last 5 being 8. What was the 5th observation?
Options:
(A) 9
(B) 8
(C) 7
(D) 6
(E) 2
(A)

## Solution
12/ (2 * 2) = 3 days
## What the question and answer could be
Some persons can do a piece of work in 12 days. Two times the number of these people will do half of that work in?
Options:
(A) 3
(B) 4
(C) 5
(D) 6
(E) 8
(A)

## Solution
Avg = [(x+2)^2 + (x-4)^2] / 2
Expanding and simplifying, (x^2 + 4x + 4 + x^2 - 8x + 16 ) / 2 = x^2 - 2x +10
## What the question and answer could be

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Which of the following is equal to the average (arithmetic mean) of (x+2)^2 and (x-4)^2?
Options:
(A) x^2
(B) x^2+2
(C) x^2-2x+10
(D) x^2+2x+10
(E) x^2+4x+5
(C)