Question

A car's speedometer has a percent error of 5%. The speedometer currently shows that the car is traveling at a speed of 60 mph.

Which statement describes what the actual speed of the car could be?

The actual speed of the car is between 30 mph and 90 mph.

The actual speed of the car is between 55 mph and 65 mph.

The actual speed of the car is between 57 mph and 63 mph.

The actual speed of the car is between 58 mph and 62 mph.

Answer 1

Im thinking D im not sure though

Answer 2

remember, the percent error is
\[ \frac{estimate - truth}{truth}= error \]
using algebra, we can write that as
\[ estimate-truth = error*truth\]
and finally
\[ estimate = truth \pm error*truth\]
so the first thing is to figure out
5% * 60
but first change 5% back to a decimal

Answer 3

we want to find
error * truth

error is 5% or 0.05
truth is 60 mph
we need to find 0.05*60

Answer 4

so 3?

Answer 5

yes
and the estimate will be truth + or - 3
in other words, 60+3 or 60-3