SOLUTION: A piggy bank contains a quarter, two dimes, a nickel, and three pennies. If one coin is taken randomly out of the bank, then replaced, and then a second coin is drawn, what is t

Algebra ->  Average -> SOLUTION: A piggy bank contains a quarter, two dimes, a nickel, and three pennies. If one coin is taken randomly out of the bank, then replaced, and then a second coin is drawn, what is t      Log On


   

Question 1140366: A piggy bank contains a quarter, two dimes, a nickel, and three pennies. If one coin
is taken randomly out of the bank, then replaced, and then a second coin is drawn, what
is the probability that the total value drawn is at least 30 cents?
Answer by greenestamps(13200) About Me  (Show Source):
You can put this solution on YOUR website!


There are 7 coins; the probability of choosing any one particular coin on each draw is 1/7. The probability of specific outcomes on two successive draws is (1/7)*(1/7) = 1/49.

Count the number of outcomes with a total of 30 cents or more using an organized list.

Two things I can think of that you want to consider when making your list:
(1) at least one of the coins drawn must be the quarter
(2) quarter then dime (for example) is a different outcome than dime then quarter

Then if you count 10 cases where the total is 30 cents or more (for example; not the right answer!), the answer to the question would be 10/49.