IIT JEE , AIEEE Forum - Mathematics , Algebra - n digits r taken @ random & multiplied then P(last digit is 1,3,7,9),P(l.. 5),P(2,4,6,8)

iitkgp_bipin

Possible digits are 0,1,2,3,4,5,6,7,8,9.... total 10 digits.

For last digit to e 1,3,7,9 : all n digits should be odd except 5 i.e. digits can be chosen among 1,3,7,9

so P = (4/10)ⁿ= (2/5)ⁿ

For last digit to be 5 at least one digit should be 5 and others should be odd.

P = ⁿC₁(1/10)(5/10)^n-1

For last digit to be 2,4,6,8 at least one digit should be among 2,4,6,8 and others can be any digit except 0 and 5.

P = ⁿC₁(4/10)(8/10)^n-1

edited : thanks nadeemoidu for correcting.

Ask & Discuss Questions with Community & Experts