Question

if 4 digit numbers greater than 5000 are randomly formed from the digits 1,3,5,7&0,what is the probability of forming a number divisible by 5 when,
1.the digits are repeated?
2.the repetition of digits is not allowed?

Answer 1

1) digits are repeated.
4 digit nos are greater than 5000, hence first digit can only be 5 or 7
for first digit as 5, total possible numbers = (5^3) -1 . One is subtracted since we don't want 5000 in our sample space.
For 7 as first digit, total numbers = 5^3
Hence sample space = 124 +125 =249

favorable -> when no. ends in 5 or 0.
Fixing 5 at end with 5 in starting -> 5^2 =25
Fixing 0 at end and 5 in starting ->5^2 -1 = 24
Fixing 5 at end with 7 in starting -> 5^2 =25
Fixing 0 at end with 7 in starting -> 5^2 = 25

Total fav outcomes = 99

Probab = 99/249

Whats your progress with 2nd part ?

Answer 2

the answer thats given in text for the first question is 2/5 & second is 3/8. but i dont know the way.

Answer 3

@Directrix can u help me please....?

Answer 4

@ash2326 can u help me please....?