In normal distributions, the 95th percentile is a value
exists within 2 standard deviations of the mean.
The mean is 175 lbs. and SD is 15 lbs. This means that Harvey's mass will be inside
2 standard deviations (respectively) of the mean. In other words, his weight
will be in the range 145 - 205 Lbs.
first set the equation equal to 0, v^2+9v+20, factor v^2+4v+5v+20, v(v+4) 5(v+4), so the 2 factors are (v+5) and (v+4), set both equal to that 0. v+5=0 v=-5 and v+4=0 v=-4, so the answer is -4 and -5