stne
1)Find the number of "ARRANGEMENTS " that can be made taking 4 letters from the word "ENTRANCE".
Please note it says Arrangements and Not selections so ENTR is Different from NTRE meaning order is important.
OA = 606
However I am not sure how to do it
As I understand, we have to make four-letter words (even meaningless) using the letters of the word ENTRANCE.
There are 8 letters. Since we have two E's and two N's, we should distinguish between the following cases:
1) Choose two E's and two N's (E,E,N,N) - 1 possibility - number of words - 4!/(2!*2!) = 6
2) Choose two E's and any two letters of the other remaining 5 distinct letters (just one N included) - 5C2 = 10 possibilities - number of words - 10*(4!/2!) = 120
3) Choose two N's and any two letters of the other remaining 5 distinct letters (just one E included) - 5C2 = 10 possibilities - number of words - 10*(4!/2!) = 120
(Identical reasoning for 2 and 3 above)
4) Choose any four letters from 6 distinct letters (just one E and one N included) - 6C2 = 15 possibilities - number of words - 15*4!= 360.
Total number of possible words 6 + 2*120 + 360 = 606.