(a) In a certain culture of bacteria the rate of increase is proportional to the numberpresent.(i) If it is found that the number doubles in 8 hours, how many may be expeetedat the end of 24 hours?(ii) If there are 10* at the end of 7 hours and 4 x 10* at the end of 9 hours, howmany were there in the beginning?(b) According to Newton's law of cooling, the rate at which a substance cools inmoving air is proportional to the difference between the temperature of the substanceand that of the air. If the temperature of the air is 32 and the substance cools from100 to 70° in 15 minutes, find when the temperature will be 12°.

Since you have posted a multiple question ,I will solve the first question for you. To get…

(a) In a certain culture of bacteria the rate of increase is proportional to the number present. (i) If it is found that the number doubles in 8 hours, how many may be expected at the end of 24 hours? (ii) If there are 10* at the end of 7 hours and 4 x 10* at the end of 9 hours, how many were there in the beginning?