Ninety-five percent of light incident on a mirror is reflected. How much light is reflected when three of these mirrors are arranged so light reflects from one after the other?
A) 85%
B) 81%
C) 90%
D) 86%
E) 95%

Question

Quizplus · Accepted Answer

When light reflects from one mirror, 95% is reflected. When it reflects from a second mirror, 95% of the remaining 5% is reflected, or 0.95 * 0.05 = 0.0475. When it reflects from a third mirror, 95% of the remaining 0.0475 is reflected, or 0.95 * 0.0475 = 0.0451. So, the total amount of light reflected is 0.95 + 0.0475 + 0.0451 = 0.8626, or 86%.

Ninety-Five Percent of Light Incident on a Mirror Is Reflected