A safety specialist was concerned about cars' speeds on a certain busy stretch of road. They randomly selected 21 cars and measured their speeds at the same point on the road. Each car was from a different time period and day, so the specialist is willing to consider the sample as representative. The speeds in the sample were strongly skewed to the left with a sample mean of overline x =96.5 km/hr . There were also a few outliers

You need to figure out at which x-value does the graph has a tangent line slope of -1.remember, the derivative is the slope of the tangent line. so find the derivative function and set it to equal -1 to find the x-value that will have a tangent line slope of 0.differentiate with the chain rule.    set the derivative to equal -1 and solve for x.      take log base 10 of both sides. also recall that  .    so the x-coord of the point of tangency is .the y-coordinate of this point of tangency can be calculated using the original function:     using point-slope form, the equation of the tangent line is      the x-intercept of this tangent line is when the graph is at y=0.    this rounds off to  .choice c.