Let us assume the number as xyz
Total outcomes = All the numbers between 100 and 400 for which the sum of digits = 10
Favourable outcomes = All the numbers between 100 and 400 for which the sum of digits = 10, and the number is divisible by 4.
P= Total Outcomes  Favourable Outcomes ​Now, for the total outcomes we have 3 cases as per the hundredth place digit.
Case-1: When the hundredth place digit = 1 (x=1)
Since the sum of digits
=10,(y+z)=9. Thus, there are 10 possible pairs for
(y,z)=(0,9),(1,8),(2,7),……,(9,0)= > 10 possibilities
Case-2: When the hundredth place digit = 2 (x=2)
Since the sum of digits
=10,(y+z)=8. Thus, there are 9 possible pairs for
(y,z)=(0,8),(1,7),(2,6),……,(8,0) = > 9 possibilities
Case-3: When the hundredth place digit = 3 (x=3)
Since the sum of digits
=10,(y+z)=7. Thus, there are 8 possible pairs for
(y,z)=(0,7),(1,6),(2,5),……,(7,0) = > 8 possibilities
For 400, the sum of the digits is 4; thus, we don't need to worry about 400.
Thus, the total outcomes
=10+9+8=27For the favourable outcomes we need to check whether the number's last two digits are divisible by 4, that is, yz is divisible by 4 or not.
For Case-1 = > the only possible values for
yz=36 and 72. Thus, 2 possibilities.
For Case-2 = > the only possible values for
yz=08,44, and 80. Thus, 3 possibilities.
For Case-3 = > the only possible values for yz = 16 and 52. Thus, 2 possibilities.
So, number of favourable outcomes
=2+3+2=7⇒P= Total Outcomes  Favourable Outcomes ​=277​