I believe the answer to your question is 10/37. The total of candies inside the bag was initially 38. Since a blue candy has already been picked and cannot be picked and cannot be replaced then the total number of candy remaining in the bag is 37. So the probability of choosing a red candy is now 10/37
So 20:4000=1:200 and 50:10000=1:200 reverse 1lb:200ft^2 100ft^2=0.5lb needs to cover 26400ft^2 100 times 264=26400 so 0.5 lb times 264=132 lb needed for entire yard
