Question 6 a) For an exponentially growing quantity with a fractional growth rate r, the doubling time is log 10 2 double log . (1 +r) Note: The units of time used for T and r must be the same. Use this formula to answer the following: A population of rats is growing at a rate of 80% per month. How long with it take the population to double in size? [ 1.18 months] b ) The ratio of the atmospheric pressure (p) at a height h km above sea level, to the pressure at sea level p, , is given by P = (0.883 ) ". Ps Make h the subject of this formula, using base 10 logarithms. h = log p - log Ps log 0.883