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in a leap year, find the probability that there are exactly [#permalink]
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08 Mar 2018, 11:38
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In a leap year, find the probability that there are exactly 5 Mondays in the month of September? a. 1/7 b. 2/7 c. 3/7 d. 4/7 e. 5/7
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Last edited by pushpitkc on 08 Mar 2018, 12:52, edited 1 time in total.
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Re: in a leap year, find the probability that there are exactly [#permalink]
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08 Mar 2018, 12:57
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kanakdaga wrote: In a leap year, find the probability that there are exactly 5 Mondays in the month of September?
a. 1/7 b. 2/7 c. 3/7 d. 4/7 e. 5/7 Since there are 30 days in the month of September, there are exactly 4 weeks and 2 extra days. There are 2 possibilities that the month will have 5 Mondays. 1. When the first day is a Monday(1,8,15,22,29) 2. When the first day in a Sunday(2,9,16,23,30) Therefore, the probability that there are exactly 5 Mondays is \(\frac{2}{7}\) (Option B)
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Re: in a leap year, find the probability that there are exactly [#permalink]
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08 Mar 2018, 23:17
September month has 30 days. Out of which the probability of having 5 monday's will occur only 2 conditions. Either the week starts with Sunday or week starts with Monday. There are 2 possibility out of 7. Ans: Option B  2/7
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Re: in a leap year, find the probability that there are exactly [#permalink]
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13 Mar 2018, 11:23
kanakdaga wrote: In a leap year, find the probability that there are exactly 5 Mondays in the month of September?
a. 1/7 b. 2/7 c. 3/7 d. 4/7 e. 5/7 Good question. Took me some time to figure it out. Since September has 30 days then it will have 5 Mondays only if the 1st day of the month is a Monday or a Sunday. Hence the probability is 2/7. So B.
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Re: in a leap year, find the probability that there are exactly [#permalink]
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15 Mar 2018, 05:47
rohan2345 wrote: kanakdaga wrote: In a leap year, find the probability that there are exactly 5 Mondays in the month of September?
a. 1/7 b. 2/7 c. 3/7 d. 4/7 e. 5/7 Good question. Took me some time to figure it out. Since September has 30 days then it will have 5 Mondays only if the 1st day of the month is a Monday or a Sunday. Hence the probability is 2/7. So B. Sorry, but how is the total possible outcome 7, is it possible for a month to have 7 Mondays . So 2 Mondays out of 7 hence 2/7 ?
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Re: in a leap year, find the probability that there are exactly [#permalink]
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15 Mar 2018, 05:58
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stne wrote: Sorry, but how is the total possible outcome 7, is it possible for a month to have 7 Mondays . So 2 Mondays out of 7 hence 2/7 ?
Hey stne , No, you didn't understand the solution properly. What we are saying is inorder to have 5 Mondays we need to have 1st day of the month either a Monday or a Sunday. Now, Probability = Number of favourable outcomes/Total number of outcomes. Number of favourable outcomes (1st day as Monday or Sunday) = 2 Total number of outcomes(1st day could be any of the 7 days) = 7 Hence, Probability = 2/7. Does that make sense?
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Re: in a leap year, find the probability that there are exactly [#permalink]
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15 Mar 2018, 06:01
It ddefinitely has to be option B. That is my answer.



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Re: in a leap year, find the probability that there are exactly [#permalink]
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15 Mar 2018, 07:25
abhimahna wrote: stne wrote: Sorry, but how is the total possible outcome 7, is it possible for a month to have 7 Mondays . So 2 Mondays out of 7 hence 2/7 ?
Hey stne , No, you didn't understand the solution properly. What we are saying is inorder to have 5 Mondays we need to have 1st day of the month either a Monday or a Sunday. Now, Probability = Number of favourable outcomes/Total number of outcomes. Number of favourable outcomes (1st day as Monday or Sunday) = 2 Total number of outcomes(1st day could be any of the 7 days) = 7 Hence, Probability = 2/7. Does that make sense? Yes now its clear, thanks a ton.
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