I'd go with 5/32 and here's my reasoning:
There are favorable and unfavorable cases to each of the five tosses, and since each case has a probability of 1/2, you'll always have a total probability of 1/2*1/2*1/2*1/2*1/2 = 1/32 for your event. The distribution is as follows:
H H H T T
T H H H T
T T H H H
T H H H H
H H H H T
H H H H H
Since each of the cases above is obtained by having a suite of 5 favorable tosses, then the total probability will be 5*1/32 = 5/32.
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Probability of atleast 3 heads
Source: Beat The GMAT — Problem Solving |
DanaJ, you did a calculation error. The number of favorable cases as per your explanation is 6 not 5.DanaJ wrote:I'd go with 5/32 and here's my reasoning:
There are favorable and unfavorable cases to each of the five tosses, and since each case has a probability of 1/2, you'll always have a total probability of 1/2*1/2*1/2*1/2*1/2 = 1/32 for your event. The distribution is as follows:
H H H T T
T H H H T
T T H H H
T H H H H
H H H H T
H H H H H
Since each of the cases above is obtained by having a suite of 5 favorable tosses, then the total probability will be 5*1/32 = 5/32.
I would go with A
3 heads or 4 heads or 5 heads
Pick 5 spots there are three ways to get 3 heads 9in consecutive tosses and 2 tails
1/32+1/32+1/32 = 3/32
For 4 consecutive heads there are 2 ways to get it in 5 tosses
2/32
5 consecutive heads there is only one choice = 1/32
3/32+2/32+1/32
= 6/32
= 3/16
3 heads or 4 heads or 5 heads
Pick 5 spots there are three ways to get 3 heads 9in consecutive tosses and 2 tails
1/32+1/32+1/32 = 3/32
For 4 consecutive heads there are 2 ways to get it in 5 tosses
2/32
5 consecutive heads there is only one choice = 1/32
3/32+2/32+1/32
= 6/32
= 3/16
IMO Bcramya wrote:I would go with A
3 heads or 4 heads or 5 heads
Pick 5 spots there are three ways to get 3 heads 9in consecutive tosses and 2 tails
1/32+1/32+1/32 = 3/32
For 4 consecutive heads there are 2 ways to get it in 5 tosses
2/32
5 consecutive heads there is only one choice = 1/32
3/32+2/32+1/32
= 6/32
= 3/16
HHHTT
TTHHH
THHHT
HHHHT
THHHH
HTHHH
HHHTH
HHHHH
= 8/32
= 1/4
OA pls?
Yes Cramya! Right!cramya wrote:Piyush,
HTHHH
HHHTH
These wont be consecutive tosses, correct?
Regards,
CR
But above represents a scenario of 3 consecutives tosses, correct?
