IIT JEE , AIEEE Forum - Mathematics , Algebra

man111

(1) find the probability that a 4 digit palindrome is divisable by 99.

plandrome is a no which is same when we read from left or right side

like

1331

akhil_o

Since its 4 digit and symmetrical

sum cannot be odd.

Hence sum=18 or 36

eg 2772

now all nos. of form abba are divisible by 99(a+b=9 or 18)

possible pairs

(0,9),(8,1)(72)(63)(54)(99) will work

(90)and (99) have only 1-1 poss each while others have 2

so we have 8+2=10 poss nos.

total no of palindromes is

all nos of form abba=9*10=90

so prob is 10/90 or 1/9

rate if righ

nudge if wrong

akhil_o

pl tell the ans ...let me confirm if i am right

akhil_o

Anyone with the answer??

bhartibhanushali

yeep right

i did it on observation