We know that
The formula for combinations is
C=n!/[(n-r)!*r!]
where
n is the total number of objects you choose from
r is the number that you choose to arrange
in this problem
n=15 students
r=4 students
C=15!/[(15-4)!*4!]-----> C=15!/[11!*4!]---> (15*14*13*12*11!)/(11!*4*3*2*1)
C=(15*14*13*12)/(24)----->C=1365
the answer is
1365
Answer:
D, 20:30
Step-by-step explanation:
At first glance, this does not seem like the correct ratio. But I'll spare you a long intro and get into it:
20:30: Divide both of them by 10
=2:3
2 x 12:3 x 12
24:36
Hope this helps!
Question #2
Erica will have to work for 14 hours in order to buy her sneakers.
How to solve:
You subtract $31 from $150 which equals to $119
You multiply 8.50 (which is the amount of money she gets paid every hour) by the answers they gave you.
8.50 multiplied by 14 is 199
Erica had to work 14 hours to make $199
Your answer is D) 14
