[latexpage]

Probability

Four different positive integers less than 10 are chosen randomly what is the probability that their sum is odd?

Solve our previous ‘questions of the day’

1.Quant Question Of The Day : 19
2. Quant Question Of The Day : 18

Quant Lessons

1.Divisibility Rule of a Number (Divisibility Test)
2. Divisors of a Number ( Number of Divisors of a number)

15 comments

  1. Mayank Khanna

    We know that odd+ even = odd. So it means, we have to choose some combination of odd and even. Now, as we see 2 odd + 2 even such as 2+4+5+7= 18 , 6+8+3+9= 26 gives even answer. ( As numbers are small so I just calculated the sum . However, if the numbers are big is there any method or rule for 4 numbers , please mention in reply sir) .
    By observing we find , we have to keep 3 number of odd and 1 of even or 3 of even and 1 of odd. So we try and probability is
    (3/5.1/5 )+(3/5+1/5)
    As we consider both cases. Now we have 6/25.
    Hence 6/25.
    I am not sure of my approach as it works well with small number but when big numbers are there it won’t and secondly it took me more than 2 minutes to do it.

  2. Mayank Khanna

    I followed the rule that odd+even=odd. Till 10 we have to choose 4 numbers, so choose it in the manner as either 3 odd and 1 even or 3 even and 1 odd. Now, we have
    (3/5).(i/5)+ (3/5).(1/5)= 6/25 or 0.24

XHTML: You can use these tags: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

Recent Forum Posts/Questions/Answers