Jane needs to walk 3 blocks south and 3 blocks east. What is the proba

Question

Jane needs to walk 3 blocks south and 3 blocks east. What is the probability that she will walk south for the first 2 blocks?

A. 1/6
B. 1/5
C. 2/5
D. 3/5
E. 4/5

CareerGeek · Accepted Answer

To reach destination, Jane needs to cover 3S & 3E blocks
--> Total ways to reach = number of ways of arranging 3S & 3E =  \frac{6!}{3!*3!}  = 20

Favorable = Taking first 2 south blocks = "Fixing" the first 2 as SS and arranging remaining 1S & 3E =  \frac{4!}{1!*3!}  = 4

Required Probability = 1/5

IMO Option B

himani2093 · Answer

Answer should be 1/5 as she is moving south first 2 steps means that she is not moving east. So 
Total options-6 
East-3
South-3

P(moving south) = 3/6 * 2/5 = 1/5

So answer = 1/5

+kudos if you liked the answer

https://gmatclub.com/static/posted_from.png     Posted from    GMAT ToolKit

Archit3110 · Answer

total ways initially ; 6!/3!*3! = 20
and now keeping 2 blocks fixed and 3 blocks east as options we have 4!/3! ways ; 4 
4/20 ; 1/5 IMO B

Businessconquerer · Answer

It is quite confusing at first if you miss a single thing

There are 3S and 3E

How do you arrange that????

6!/(3!3!) These are total number of ways

Now we have to fix first two as S

(S S) (4 OTHERS (3E, 1S))

The way these can be arranged 
4!/3!

not 5!/3! because you've fixed the first two

Answer becomes

(4!/3!)/(6!/3!3!)

Ans: 1/5

I hope this helps

SPatel1992 · Answer

pravalithota · Answer

favourable outcomes= 3c2
total outcomes = 6c2
p=3/15=1/5

answer- B

ScottTargetTestPrep · Answer

Assuming Jane will not walk north or west, she will walk south three blocks and east three blocks; totalling six blocks. The probability that the first block she walks is south is 3/6 = 1/2. After walking one block south, she needs to walk two more blocks south and three blocks east. Thus, the probability that the second block she walks is also south is 2/5. In total, the probability that the first two blocks she walks are both south is 1/2 x 2/5 = 1/5.

Answer: B

bumpbot · Answer

Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.

Jane needs to walk 3 blocks south and 3 blocks east. What is the proba

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Problem Solving (PS) Questions

Jane needs to walk 3 blocks south and 3 blocks east. What is the proba

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards