### Home > CALC > Chapter 11 > Lesson 11.4.1 > Problem 11-130

11-130.

**Multiple Choice:**The luminous intensity*E*of a light bulb, measured in lumens per ft^{2}, varies inversely as the square of the distance*s*from the bulb.*E*= 5.2 lumens per ft^{2}when*s*= 5 ft for a 100 watt bulb. If you are moving away from a 100 watt bulb at a speed of 2 feet per second and you are 3 feet from the bulb, the luminous intensity is changing at the rate of: Homework Help ✎

When *s* = 3, *E* = ?

Substitute in the known values and solve for *E′*.