When the firecracker hits the ground, H(t) = 0.0 = -16t^2 + 90t + 160 Using the quadratic formula,t = (-90 +- sqrt(90^2 - 4(-16)(160))) / 2(-16)t = -1.42 ort = 7.04
The negative time is extraneous. Therefore,t = 7.04 s.
Seven Seconds is your answer!
I pretty sure the answer is 3.2 hours. I'm not completely sure though....
Answer:
The product of the original numbers: xy
The product of the altered numbers (.75x)(.5y), or 0.375xy
The product has decreased by 1 - 0.375, or 0.625, or 62.5%
