Question

Mr. Cohen is a scientist who is testing the efficiency of a 9 V battery by measuring how much electrical energy it releases. He determines that 7 V of energy is converted to electrical energy. Which of these formulas shows how to calculate the efficiency of the battery?

Answer 1

Answer:

D. (7 ÷ 9) × 100

Explanation:

In order to solve this problem we need the answers of the problem, performing an internet search this problem is found, with the different answer options

A. (7 − 9) × 100

B. (9 − 7) × 100

C. (9 ÷ 7) × 100

D. (7 ÷ 9) × 100

Returning to the problem of the total energy of 9V only 7 volts were used. If we make a rule of three we realize that:

$100 = 9V\\x = 7\\x = \frac{7*100}{9}$

x = 77.77%

In this way we determine that the answer is D.