The mean is the average of the numbers.
It is easy to calculate: add up all the numbers, then divide by how many numbers there are.
Let the number of sit-ups you have to do Sunday be x. Then the sum of all sit-ups is
100+65+120+150+90+0+x=525+x.
The number of days is 7.
Thus, the mean is
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You know that the mean number of sit-ups per day is 100, equate these two means and solve the equation:

Answer: 175 sit-ups
Lets first convert everything to inches.
6 feet= 12*6 = 72 + 10 = 82 inches
8 feet= 12*8 = 96+9 = 105 inches
Now add!
82+105 = 187
Now convert them back to feet.
187/12 = 15 feet
12*15 = 180
187 - 180 = 7 inches
15 feet. 7 inches.
Final answer: B. 15 ft. 7 in.