Probability and Time Distance Question

Question

Hi Everyone,

Please find attached the document having questions for probability and time distance.

Thanks in advance.

Regards,
Aban

maliyeci · Answer

For q1;

The total time is = time traveled 60 mph + time traveled 30 mph.
(x-5)/60 hours + 5/30 hours = (x+5)/60 hours.
if he had traveled at a constant 60 mph speed. His travel time would have been x/60 hours.
Thus we get the percentage =>
Time difference = (x+5)/60-x/60= 5/60 hours = 1/12 hours.
Time for constant travel = x/60 hours. 
So the percentage difference is (1/12).100 / (x/60)= 5.100/x = 500/x %

maliyeci · Answer

For question 2;
There are 4 cases;
1- St.A plays good
2- St.A plays bad but st.B plays good
3- St.A and St.B plays bad but st.C plays good.
4-All plays bad.
Prob of 1st case is 0,3
Prob of 2nd case is 0,7.0,3
Prob of 3rd case is 0,7.0,7.0,3
Prob of 4th case is 0,7.0,7.0,7
Sum of all is 0,3 + 0,21 + 0,147 + 0,343 = 1 
In only the last case the song is bad. So the prob. that a good song is played is 1-0,343=0,657
D

irajeevsingh · Answer

For everyone's benefit 
Q1
 https://img170.imageshack.us/img170/639/82664065.png

irajeevsingh · Answer

Q2
 https://img257.imageshack.us/img257/400/86505699.png

irajeevsingh · Answer

Q2)
Prob of Leo to hear a song he likes = 
Prob of Radio A playing songs which Leo likes
+Prob of Radio B playing songs which Leo likes
+Prob of Radio C playing songs which Leo likes
= 0.3 + 0.3 * 0.7 +0.3 *0.3 *0.7
= 0.3+0.21+0.147
=0.657 
Option D

irajeevsingh · Answer

Time spent with 5 mile@30mph = X-5/60 + 5/30 = (X+5)/60
Time spent with entire trip @60mph = X/60. 
Time Diff = 1/12 
Q: % of diff with total time @60mph: 
(1/12) / (X/60)*100
= (500/X)%

pareekpuneet · Answer

Hi Guys,

Time distance was so simple... i just screwed it ... dont know y ... thanks for that one .. but for the probability one can anyone please elaborate the below mentioned logic for me as i dont know much about the proability:

1. Radio A --> 0.3 (I understand)
2. Radio B --> 0.3 (For radio B) * 0.7 (for the case where radio A is not played)
3. Radio C --> 0.3 (For radio C) * 0.3 (Why this 0.3 and not 1 - 0.3 = 0.7) * 0.7.

I dont understand the logi behind two times 0.3 in the last case as mentioned by irajeevsingh.

i know it might b simple... not clicking to me

....

Thanks for your help.

Regards,
Aban

.... Thanks for your help. Regards, Aban

maliyeci · Answer

Look at this file. This problem is a decision tree problem.

Probability and Time Distance Question

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