A bag contains 4 white balls and some red balls. If the probability of drawing a white ball from the bag is `2/5,` find the number of red balls in the bag.

Explanation

No. of white balls=`4`
Let the number of red balls be `x`
Hence the total number of balls will be `x + 4`
P(drawing a white ball from the bag)=`"No. of white balls"/"Total number of balls"`
`2/5=4/(x+4)`
`2(x+4)=4xx5`
`x+4=10`
`therefore x=10-4=6`
Hence the number of red balls is `6`