It is done by this formula
combinations = n! / [r! * (n - r)!]
combinations = 15! / [4! * 11!]
combinations = 15 * 14 * 13 * 12 * 11! / [4! * 11!]
combinations = 15 * 14 * 13 * 12 / 4 * 3 * 2
combinations = 15 * 7 * 13
combinations = 1,365
answer is b
Answer:
54
Step-by-step explanation:
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Answer: Three quarters (30 ml) is made up of a 36% acid solution.
Step-by-step explanation:
Since we have given that
Total amount of solution = 40 ml
One- quarter of the solution is given by

Three-quarter of the solution is given by

According to question, we have
10 ml of solution is made up of = 20% of acid solution
30 ml of solution is made up of = say<em> 'c </em>' of acid solution
40 ml of solution is made up of = 32 % of acid solution
So, our equation becomes,

Hence, three quarters (30 ml) is made up of a 36% acid solution.
The answer is 512 ! To find this answer you can try 4*2 8 times since 4 is multipled by 2 continuously as a pattern.