sum of a five digit number is 41 find the probability such that the number is divisible by 11
In order to get the sum as 41, the following 5 digit combination exist:
99995--->number of 5 digits =5
99986--->number of 5 digit =20
99977--->number of 5 digit =10
99887--->number of 5 digit =30
98888--->number of 5 digit =5
Now, 70 such number exists.
Now for a 5 digit number of form (pqrst) to be divisible by
11(p+r+t)-(q+s)=11, also (p+r+t)+(q+s)=41
p+r+t=26, q+s=15
(p,r,t)=(9,9,8) and (q,s)=(8,7) --------(i)
or (p,r,t)=(9,9,8) and (q,s)=(9,6) --------(ii)
Using 1st equation we can construct 3!/2! ×2!=6 numbers.
Using 2nd equation we can construct 3!/2! ×2!=6 numbers.
Number of favorable cases = 12.
Hence, required probability = 12/70 = 6/35
99995--->number of 5 digits =5
99986--->number of 5 digit =20
99977--->number of 5 digit =10
99887--->number of 5 digit =30
98888--->number of 5 digit =5
Now, 70 such number exists.
Now for a 5 digit number of form (pqrst) to be divisible by
11(p+r+t)-(q+s)=11, also (p+r+t)+(q+s)=41
p+r+t=26, q+s=15
(p,r,t)=(9,9,8) and (q,s)=(8,7) --------(i)
or (p,r,t)=(9,9,8) and (q,s)=(9,6) --------(ii)
Using 1st equation we can construct 3!/2! ×2!=6 numbers.
Using 2nd equation we can construct 3!/2! ×2!=6 numbers.
Number of favorable cases = 12.
Hence, required probability = 12/70 = 6/35