A box contains 10 red marbles, 13 blue marbles, 6 green marbles and 7 white marbles. What is the probability of selecting a red marble?

Total number of marbles = 10+20+30 = 60 out of which 20 are blue.

Probability of first marble being blue = 20/60

Probability of second marble being blue = 19/59

Probability of third marble being blue = 18/58

Probability of fourth marble being blue = 17/57

Probability of fifth marble being blue = 16/56

So probability of all marble being blue when five marbles are drawn from the box = (20/60)*(19/59)*(18/58)*(17/57)*(16/56) = 34/11977 = 0.00283877432

Step-by-step explanation:

i assume that by 5 you mean 5 gallons.

(20)(0.25) = 15

removing 15 gallons reduces the tank from 20 to 5.

answer: ouch. thats difficult

step-by-step explanation: