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the probability of getting a number between 1 and 100 which is divisible by 7 is ___?

the first number b/w 1 and 100 divisible by 7 is  7

the last number b/w 1 and 100 divisible by7 is 98

an = a + ( n- 1) d

98 = 7 + 7n - 7

98 / 7= n

n= 14

favorable outcomes=14

probability=14/98

  = 1/7

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Smallest number divisible by seven = 7

Largest number divisible by seven = 98

Here a = 7 , d = 7 an = 9

an = a + (n-1)d

Substituting the value

98 = 7 + (n-1)7

98 - 7 = (n-1)7

91 = (n - 1)7

91/7 = (n-1)

(n-1) = 13

n = 14

Hence the number of  favourable  outcomes = 14

Total number of outcomes  = 100

Probability of getting a number between 1 and 100 is 14/100 or 7/50  

Hope its correct

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But total numbers are 100 so how come 14/<font size=25>98</font>

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I think the question is between 1 and 100 

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i dont know . maybe shubhi anand is right

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between means multiples between so total has to be 100...

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In the sample question from where I have asked, answer given is 25/98...

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Hey there must be the correct ans provided and another point to be noted is that total no is between 1 to 100 so total no of outcomes is 100

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I agree with SHUBHI ANAND that 100 is total but how to get 25...

Actually, we all see the answers first and then solve questions!! :)

  • 4

25? is it the no. of favourable conditions ?

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no no.. ans given is25/98(it maybe wrong)

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Where did you get this question from? 

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dont always rely on that answers . they too may be wrong.

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@ Hazeem Mohsin Abdullah : I agree with you but we both are having different ans how will we clear our doubt? any solution ?

  • 2

the answer in sample paper says that the number of outcomes is 98. i dont get it.

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@Shubhi is correct. 

@Hazeem WHat you have written is -

"favorable outcomes=14

probability=14/98"

Why you have taken probability as 14/98? It should be 14/100 which is 7/50.
The denominator is the no. of possible outcomes. And possible outcomes are 100 and not 98.

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Or it may be 98 because it is saying between 1 and 100. So we are not going to include 1 and 100.

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WE all are TWO SIDED

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I would request an expert to solve this sum

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me too 

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no ans??????????????

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 well.. the ques itself says "between 1 & 100" 

this simply implies that a number (n) which is 

1<n<100.

where n is an integer(as per the ques.)

so total possible outcomes = 98

but the total possible outcomes would have been 100 only and only if the question said - "find the probability of getting a number divisible by 7 in first 100 natural numbers."

hope it helps.. 

cheers.. :)

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total possible outcome is 14 . numbers are 7 14 21 35 42 49 56 63 70 77 84 91 and 98 .. the question says between 1 and 100 in this 1 and 100 will not be included so total noes. are 98 so answer is 14/98 = 1/7

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As it is giv n that the numbers are between 1-100 we must not count 1 or 100 so there are 98 numbers between 1 and 100 .
so there are 14 numbers between 1-100 that are divisible by 7
so probability is 14/98
P(E)=1/7
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How 98?
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Total no. Of outcomes is 98 becoz the question says b/w 1 and 100. So,1 and 100 cannot be included
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