A bowl contains 18 raffle tickets, numbered 1 through 18. If two raffle tickets are chosen at random from the bowl, what

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A bowl contains 18 raffle tickets, numbered 1 through 18. If two raffle tickets are chosen at random from the bowl, what is the probability that both tickets are even numbers?

A. \(\dfrac29\)

B. \(\dfrac4{17}\)

C. \(\dfrac14\)

D. \(\dfrac12\)

E. \(\dfrac{33}{34}\)

[spoiler]OA=B[/spoiler]

Source: Princeton Review
Source: — Problem Solving |

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VJesus12 wrote:
Thu Jun 04, 2020 7:01 am
A bowl contains 18 raffle tickets, numbered 1 through 18. If two raffle tickets are chosen at random from the bowl, what is the probability that both tickets are even numbers?

A. \(\dfrac29\)

B. \(\dfrac4{17}\)

C. \(\dfrac14\)

D. \(\dfrac12\)

E. \(\dfrac{33}{34}\)

[spoiler]OA=B[/spoiler]

Solution:

There is a 9/18 chance of selecting an even number with the first pick and a 8/17 chance of selecting an even number with the next pick; thus, the probability of selecting 2 even numbers is 9/18 x 8/17 = 1/2 x 8/17 = 8/34 = 4/17.

Answer: B

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VJesus12 wrote:
Thu Jun 04, 2020 7:01 am
A bowl contains 18 raffle tickets, numbered 1 through 18. If two raffle tickets are chosen at random from the bowl, what is the probability that both tickets are even numbers?

A. \(\dfrac29\)

B. \(\dfrac4{17}\)

C. \(\dfrac14\)

D. \(\dfrac12\)

E. \(\dfrac{33}{34}\)

[spoiler]OA=B[/spoiler]

Source: Princeton Review
P(both even) = P(1st ticket is even AND 2nd ticket is even)
= P(1st ticket is even) x P(2nd ticket is even)
= 9/18 x 8/17
= 4/17

Answer: B

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Brent
Brent Hanneson - Creator of GMATPrepNow.com
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Total even nos = 9

Probability to pick first even number = 9/18

Probability to pick second even number (considering no replacement) = 8/17

Combining the 2 = 1/2 * 8/17 = 4/17