## JOYAL 2 years ago 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?

1. sauravshakya

Isnt it 2/5

2. sauravshakya

for 1st case

3. JOYAL

4. sauravshakya

To be divisible by 5 the last digit must be either 0 or 5

5. sauravshakya

So, 2/number of different digits we can choose for the last digit = 2/5

6. JOYAL

so,what's the answer for 2 case??????????????

7. sauravshakya

(1*1*3*2 + 1*2*3*2)/(2*4*3*2)

8. sauravshakya

3/8

9. JOYAL

how did you get that !!!

10. sauravshakya

If the first digit is 5 then the last digit must be 0 If the first digit is 7 then the last digit can be either 0 or 5

11. sauravshakya

Which gives No. of numbers divisible by 5 greater than 5000 = 1*1*3*2+1*2*3*2

12. sauravshakya

And No. of numbers that can be formed greater than 5000= 2*4*3*2 as the first digit must be either 5 or 7

13. sauravshakya

got it?

14. JOYAL