PLEASE HELP 1 You diluted a bacterial culture 106 plated out

PLEASE HELP!!!!!

1. You diluted a bacterial culture 10^6, plated out 0.2 mL and got 45 colonies growing on the plate. How many bacteria/mL were in the original undiluted cuture?

2. You have a microtube containing 1 mL of a solution with 4.3 x 10^4 cells/mL and you are to produce a solution that contains 43 cells/mL. What serial dilutions must you perform?

Solution

Ans(1):

given that 0.2 ml produces 45 colony

to convert 0.2 ml into 1 ml we need to multiply by 5

then 1 ml will produce =5 * 45 = 225 colony

hence culture in original undiluted solution = 225 x 10^6

= 1.25 x10^8

Hence answer is 1.25 x10^8