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Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

A. 1/2

B. 2/5

C. 8/15

D. 9/20

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(03-14-2014, 05:00 PM)vaniinstitute Wrote: Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

A. 1/2

B. 2/5

C. 8/15

D. 9/20

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(03-14-2014, 05:00 PM)vaniinstitute Wrote: Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

A. 1/2

B. 2/5

C. 8/15

D. 9/20

Answer is D. 9/20

Not conform. please reply true answer.

Thank you !

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(03-15-2014, 05:42 PM)kazisbi Wrote: (03-14-2014, 05:00 PM)vaniinstitute Wrote: Tickets numbered 1 to 20 are mixed up and then a ticket is drawn at random. What is the probability that the ticket drawn has a number which is a multiple of 3 or 5?

A. 1/2

B. 2/5

C. 8/15

D. 9/20

Answer is D. 9/20

Not conform. please reply true answer.

Thank you !

the answer will be 2/5.

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Ans should be 9/20

Probability ticket is multiple of 3 occurs when ticket num is either 3,6,9,12,15 or 18 ie 6 options. So 6/20

similarly for 5 we have 5,10,15,20 ie 4 options.

which is 4/20

Add both for probability of 3 or 5 but subtract 15 ka case as we have counted it twice in 3 as well as 5 ka case.

So answer is 9/20

Or just count multiples of 3 and 5 in 1-20 and divide them by twenty. Dont count 15 twice.

Hope it helps.

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