#### Answer

C. 75 dollars (is the best estimate for the cost of the 10 calculators)

#### Work Step by Step

We are told that half of the 10 people ordered calculators costing 6.95 each. Therefore, this means 5 people paid approximately 7 dollars per calculator. 5 x 7 = 35 dollars.
Then, there are still 5 more people buying calculators. Since we don't know what price each paid, we can average the lowest priced calculator and the highest price calculator. Estimating, the lowest cost is about 5 dollar and the highest price is about 13 dollars. The average of 5 and 13 is 9 dollars. So, if the other 5 people paid an average of 9 dollars per calculator, then 5 x 9 = 45 dollars. Add the 35 and 45 and we get 80 dollars.
The answer choice closest to this is answer C, 75 dollars.