John has invested $6,000,part at 6% simple interest and part at 8% simple interest. If his interest for the year from both investments is $400. The amount invested at 6% is

What is the solution to the system of equations? (–2, –8) (–1, –5) (0, –2) (2, 4)

An airplane travels at an unknown elevation before it descends 3 miles to an elevation of 15 miles. find the elevation of the plane before its descen.

Assume that adults have iq scores that are normally distributed with a mean of mu equals 100 and a standard deviation sigma equals 20. find the probability that a randomly selected adult has an iq between 80 and 120.assume that adults have iq scores that are normally distributed with a mean of mu equals 100 and a standard deviation sigma equals 20. find the probability that a randomly selected adult has an iq between 80 and 120.