A sofa with an original price of $600 is put on sale for $480. What is the percentage discount on the cost of the sofa?

On a string instrument, the length of a string varies inversely as the frequency of its vibrations. an 11-inch string has a frequency of 400 cylces per second. find the frequency of a 10-icnch string.

Suppose babies born after a gestation period of 32 to 35 weeks have a mean weight of 25002500 grams and a standard deviation of 800800 grams while babies born after a gestation period of 40 weeks have a mean weight of 27002700 grams and a standard deviation of 385385 grams. if a 3232-week gestation period baby weighs 21252125 grams and a 4040-week gestation period baby weighs 23252325 grams, find the corresponding z-scores. which baby weighs lessless relative to the gestation period?

The ideal weight of a nickel is 0.176 ounce. to check that there are 40 nickels in a roll, a bank weighs the roll and allows for an error of 0.015 ounce in total weight