In United States Currency, a Nickel is Worth 5 Cents GMAT Problem Solving

Question: In United States currency, a nickel is worth 5 cents, a penny is worth 1 cent, and a dime is worth 10 cents. 100 cents equals one dollar. If a hand purse contains 6 nickels, 5 pennies and 4 dimes, what is the probability of picking a coin other than a nickel twice in a row if the first coin picked is not put back?

  1. 8/25
  2. 12/35
  3. 13/35
  4. 9/25
  5. 17/25

Correct Answer: B

Solution and Explanation:
Approach Solution 1:

In this case it would be easier to calculate the probability in direct way: non−nickel/all∗non−nickel−1/all−1= 9/15∗8/14= 12/35.

The problem in your solution is that the opposite probability of two non-nickel coins in a row is not two nickel in a row, it's two nickels in a row plus either of two coins from two is nickel, (so basically the probability of at least one nickel from two picks): 6/15∗5/14+2∗6/15∗9/14= 23/35

P=1−23/35= 12/35

Approach Solution 2:
There are 15 coins total. 5P + 4D = 9 coins that give me the desired outcome.

For the first pick, total outcomes = 15. Desired outcomes = 9. Probability of desired outcome is 9/15: We have 9 chances out of 15 total to get a D or a P.

The total number of coins is now 14. And there is one fewer coin in the desired group. So for second pick, probability of desired outcome is 8/14
9/15 *8/14= 12/35

Approach Solution 3:
probability of picking a coin other than a nickel (first turn)= 9/15
probability of picking a coin other than a nickel (first turn)= 8/14

P= (9/15)*(8/14)= (3/5)*(4/7)= 12/35

“In United States currency, a nickel is worth 5 cents”- is a topic of the GMAT Quantitative reasoning section of GMAT. To solve GMAT Problem Solving questions a student must have knowledge about a good amount of qualitative skills. GMAT Quant practice papers improve the mathematical knowledge of the candidates as it represents multiple sorts of quantitative problems.

Suggested GMAT Problem Solving Samples

Fees Structure

CategoryState
General15556

In case of any inaccuracy, Notify Us! 

Comments


No Comments To Show