Guest

if four positive integers are taken and at random and multiplied together,then the probability that the last digit is 1,3,7 or 9 is

if four positive integers are taken and at random and multiplied together,then the probability that the last digit is 1,3,7 or 9 is

Grade:12

1 Answers

Aman Bansal
592 Points
12 years ago

dear pankaj,

last digit of product will be 1,2,3,4,5,6,7,8or9 & only if each of the n positive integers ends in any of these integers.now probablity of integer ending with 1,2,3,4,5,6,7,8,or9 is 8/10or4/5 therefore probablity that last digit of the product of n integers is 1,2,3,4, 5,6,7,8,9 is (4/5)n .next the last digit will be 1,3,7,9 & if only if each of positive integers ends with 1,3,7,or9.the probablity of an integer to end in 1,3,7,9 is 2/5.

therefore probablity or the product of n positive integers end in 1,3,7,9 is (2/5)n

hence probablity of required event is (4/5)n -(2/5)n

We are all IITians and here to help you in your IIT JEE preparation.

Now you can win exciting gifts by answering the questions on Discussion Forum. So help discuss any query on askiitians forum and become an Elite Expert League askiitian.

Now you score 5+15 POINTS by uploading your Pic and Downloading the Askiitians Toolbar : Click here to download the toolbar.. 

AMAN BANSAL

Think You Can Provide A Better Answer ?