The radioisotope Mo-91 has a t1/2 of 15.5min. A sample decays at the rate of 954counts/min (954cpm). After how many minutes will the decay be at 7.45cpm? (Step by step please)

Write the point-slope form of the line passing through (2, -12) and parallel to y=3x.

If 30 lb of rice and 30 lb of potatoes cost ? $27.60? , and 20 lb of rice and 12 lb of potatoes cost ? $15.04? , how much will 10 lb of rice and 50 lb of potatoes? cost?

You are standing next to a really big circular lake. you want to measure the diameter of the lake, but you don't want to have to swim across with a measuring tape! you decide to walk around the perimeter of the lake and measure its circumference, and find that it's 400\pi\text{ m}400? m. what is the diameter dd of the lake?