Step-by-step explanation:
x = Alice's money
y = Mio's money
z = Grace's money
x + y + z = sum
there are originality 5+4+3 = 12 parts of the money shared between them.
x = 5/12 sum
y = 4/12 sum
z = 3/12 sum
after the money transfer we are only having 4+3+2 = 9 parts of the same money distributed.
so, we are dealing with 1/9 parts.
let's bring everything to 1/36 to be able to truly compare things.
therefore
x = 15/36 sum
y = 12/36 sum
z = 9/36 sum
15/36 sum + 10 = 16/36 sum
because 4/9 = 16/36
10 = 1/36 sum
sum = 10×36 = £360
so, together they have £360.
and they had before the £10 transfer £150, £120, £90.
after the £10 transfer they had £160, £120, £80.
The first selection can be any one of the 8.
For each one ...
The second selection can be any one of the remaining 7.
For each one ...
The third selection can be any one of the remaining 6.
For each one ...
The fourth selection can be any one of the remaining 5.
Total number of ways to select four = (8 x 7 x 6 x 5) = 1,680 ways
BUT ... There are not 1,680 different groups of 4 .
Each group of 4 can be selected in (4 x 3 x 2) = 24 different ways.
So, although there are 1,680 different ways to select 4 singers,
there are only
(1,680 / 24) = 70 different groups of 4
that you can end up with.
Without considering the sign:
It's sigma(1 to 5, 5k+2)
Since the first item is minus, you simply add (-1)^k
So it's sigma(1 to 5, (-1)^k * (5k+2)
I choose A
Answer:
Plug the formula in to your calculator
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Step-by-step explanation:
