Live GMAT classes with Target Test Prep start Nov 21 and Nov 22. First class free.
See classesLearn live with an expert or move at your own pace. Every option includes the complete TTP study system.
Target Test Prep was voted #1 Best Test Prep in the 2026 Newsweek Readers’ Choice™ Awards.
with Josh Braslow, 20+ years in test prep
Self-paced EA prep. Study on your schedule.
with
Complete access from day one. Study on your schedule.
Total no of outcomes = 2^4rahul.s wrote:A jar contains equal amounts of green jellybeans and red jellybeans. Mark selects at random one jellybean at a time from the jar, notes its color, and returns it to the jar. If he repeats this process four times, what is the probability that he selects 3 green jellybeans and 1 red jellybean?
A) 1/4
B) 3/16
C) 1/8
D) 1/16
E) 1/64
OA: A
[spoiler]my solution: i assumed 4 jellybeans in each jar. we need 3 green and 1 red = (1/2 + 1/2 +1/2) * 1/2 = 3/6 * 1/2 = 1/4. but the OE was different. is it correct?[/spoiler]
From The bag you can either take out a Red one or a green one Denoted By R or Grahul.s wrote:ajith,
could you please simplify that for me? why is it 2^4? why are the the favorable outcomes = 4? where did i err?
rahul.s wrote:A jar contains equal amounts of green jellybeans and red jellybeans. Mark selects at random one jellybean at a time from the jar, notes its color, and returns it to the jar. If he repeats this process four times, what is the probability that he selects 3 green jellybeans and 1 red jellybean?
A) 1/4
B) 3/16
C) 1/8
D) 1/16
E) 1/64
OA: A
[spoiler]my solution: i assumed 4 jellybeans in each jar. we need 3 green and 1 red = (1/2 + 1/2 +1/2) * 1/2 = 3/6 * 1/2 = 1/4. but the OE was different. is it correct?[/spoiler]
I used Stuart Kovinsky's coin flip approach to solve this question in less than 30 seconds!!!bhumika.k.shah wrote:Hey ,
can anyone explain the formula way ?? if there are 4 green colored jellybeans and 4 red colored jelly beans????
