The Intensity of light (in foot-candes) varies inversely as the square of x. the distance in foot from the light source. The intensity of light 2 from the source is 90 foot-candies. How far away is the source if the intensity of light is 7 foot-candies?

The intensity of light is 7 foot candles when the distance from the light source is ? feet
(Round to two decimal places as needed)

Find the domain and range of the following function f(x) = 51x - 21+ 4

Which of the following is a solution of z^6 = 64i? 2(cos105° + isin105°) 2(cos120° + isin120°) 2(cos135° + isin135°) 8(cos15° + isin15°)

1. according to the internal revenue service, the mean tax refund for the year 2007 was $2,708. assume the standard deviation is $650 and that the amounts refunded follow a normal probability distribution. a. what percent of the refunds are more than $3,000? b. what percent of the refunds are more than $3,000 but less than $4,000? c. what percent of the refunds are less than $2,000?