Question

For Mr. Fujimoto's class, there are 7 possible assignments. However, students only have to choose 5 assignments to complete and submit. If the order in which the students submit the assignments doesn't matter, how many different combinations of 5 are there?

Answer 1

Combinations, huh?
Remember, there are seven, you choose five.
Seven, choose five.

7C5
can you calculate that? :)

Answer 2

you multiply?

Answer 3

Not quite.
There's a formula here..
\[\Large _nC_r = \frac{n!}{r!(n-r)!}\]

Answer 4

I dont see your formula, it just says Math processing error

Answer 5

That's a problem :D
Okay, then the formula goes...
nCr = n!/(r!)(n-r)!

with that in mind, what is 7C5?

Answer 6

this girl just told me it was 21

Answer 7

how about that, right? :D

Answer 8

Thank you so much for your help. I became a fan of yours:)

Answer 9

but I wasn't able to help T.T
anyway, whoever that girl was, she was right.

it would have been better if you could find the answer yourself, though :P

Answer 10

yea, ikr, but just to be sure it is 21 correct

Answer 11

yes, it's 21.

Answer 12

thanks alot :D

Answer 13

Six friends are at the school carnival. They all want to go on the same ride, but only three people can go on the ride at one time. How many different combinations of three riders are possible?

Answer 14

What did the girl say? :3

Answer 15

I figured it out already

Answer 16

I thought you might. :D
Answer?

Answer 17

When Marek went to the bakery to order a cake for his mother's birthday, the baker asked him what colors he wanted on his cake. The bakery has twelve different colors to choose from and allows you to select six for your cake. Since the order of the colors does not matter, how many different ways can Marek choose the six different colors?

Answer 18

Look, there's a pattern here.
You choose some stuff from a larger set of stuff.
And here's how to do it...
Say, in the first question, you choose 5 from 7
The answer is multiply every number from 7 downwards until you get five numbers
7x6x5x4x3
and multiply everything from 1 upwards until you get five numbers
1x2x3x4x5

Divide the two numbers, you get the answer, which is 21.

Here, you choose 6 from 12.
do the math :)

Answer 19

12x11x10x9x8x7 ??

Answer 20

this is just the top part.
what about the bottom part?
Multiply from 1 upwards until you get six factors :)

Answer 21

1x2x3x4x5x6

Answer 22

Okay, good.
Now divide the top part by the bottom part, that's your answer :)

Answer 23

I got 924

Answer 24

That's correct lol
well done XD

Are you allowed to use a calculator?

Answer 25

somewhat yes

Answer 26

a scientific calculator?

Answer 27

thanks for the medal.... means a lot, lol

Answer 28

Well, you got it right yourself, this time, without relying on some girl :3

Answer 29

http://diagnostic.achievementseries.com/cdn/1/_graphics_math_13620b/12e697c5-dac5-4123-97fb-988027a22b68.gif can you help me with this one

Answer 30

I don't know what to do with it :)

Answer 31

I have no idea how to do it and you seem pretty good at math

Answer 32

yes, but what you posted looked just like a weird expression, and no instructions whatsoever :D

Answer 33

nevermind