The number of ways that he can make the fruit salad if it must contain watermelon is 35.
<h3>What is Permutation and combination?</h3>Selection of the one object from the given samples with replacement or without replacement is called as the permutation. The selection of the items from the sample as they are different with each other.
The salad contains water melon, now we have to select 4 more fruits out of 7.
Using combination
= n! / r! (n-r)!
= 7!/ 4! (7-4)!
= 7*6*5*4! / 4! * 3*2
= 35
Hence, number of ways that he can make the fruit salad if it must contain watermelon is 35.
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