Suppose we have: I am new at this - (5 words) how many 4 worded sentences can we make with this if "new" and "this" must appear in the sentence.
I think its :
.# of sentences we can make with any word in it - # of sentences we can make with no mention of "new" and "this" in them
so: $5^4 - 3^4 = 544$
Is that the right way of doing these type of questions? Thanks
So we just got the solutions from the professor and it seems the answer was 150 He did it by saying:
"new" and "this" appear once: $3c2 *4!$ "new" appears twice, "this" once: $3c1 * 4!/2! $ "this" appears once, "new" twice: $3c1 * 4!/2! $ "this", "new" appear twice: $4!/(2!*2!)$