JOYAL
if 4 digit numbers greater than 5000 are randomly formed from the digits 1,3,5,7&0,what is the probability of forming a number divisible by 5 when, 1.the digits are repeated? 2.the repetition of digits is not allowed?
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sauravshakya
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Isnt it 2/5
sauravshakya
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for 1st case
JOYAL
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yes... please explain the steps...
sauravshakya
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To be divisible by 5 the last digit must be either 0 or 5
sauravshakya
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So, 2/number of different digits we can choose for the last digit = 2/5
JOYAL
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so,what's the answer for 2 case??????????????
sauravshakya
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(1*1*3*2 + 1*2*3*2)/(2*4*3*2)
sauravshakya
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3/8
JOYAL
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how did you get that !!!
sauravshakya
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If the first digit is 5 then the last digit must be 0
If the first digit is 7 then the last digit can be either 0 or 5
sauravshakya
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Which gives
No. of numbers divisible by 5 greater than 5000 = 1*1*3*2+1*2*3*2
sauravshakya
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And No. of numbers that can be formed greater than 5000= 2*4*3*2
as the first digit must be either 5 or 7
sauravshakya
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got it?
JOYAL
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yes.thanks....
can you answer 1 more question please?
sauravshakya
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Okay.... but post it seperately