The population of a city increases exponentially at a rate of x% every 5 years. in 1960 the population was 60100 in 2015 the population was 120150

Plug the numbers into the exponential growth formula: 

Now work backwards to get the
1)Divide 120150 by 60100 to get 1.998668885
2) Find the 11th root of ANS:

3) Minus 1 from your answer to give 0.064976629
4)Multiply your answer by 100 to give you the rate of x%, which is 6.5 to 1d.p
x=6.5 (1 d.p.)
Btw, this answer also works if you plug it back into the equation

Number 40 is a rational number glad i could