in such qs always write down the number of times an alphabet is being repeated...p=2 s=2 h=1 i=1 n=1 e=1 a=1http://www.xtremepapers.com/papers/CIE/Cambridge International A and AS Level/Mathematics (9709)/9709_s11_qp_62.pdf
Problem no 4 (iii).
sm1 to help plz.. thnks!
select 4 letters which contain NO P and either 1s or 2s. First vl solve for 1s
-since you know that you have to take that s for sure u wont select it hence its 5c3 this means u have selected 3 letters from h i n e a.
-same goes for 2s but this time u have to select 2 letters from h i n e a= so its 5C2 hence sum them up to get 20.