The ratio of girls to boys in Liza’s classroom is 5 to 4

1 answer:

5 0

The answer is 15. There are more girls than boys. 27 divided by 2 is 13.5. As the ratio is 5:4 the number of girls must be higher than 13.5, which cancels out 12 and 9. 54 is too great so the answer is 15.

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3000 exercise books are arranged into 3 piles. The first pile has 10 more books than the second pile. The number of books in the

pochemuha

Answer:

598 books

Step-by-step explanation:

Let x be the number of books in the 3rd pile. We will have then:

1st pile: 2x + 10

2nd pile: 2x

3rd pile: x

3000 = (2x + 10) + (2x) + (x)

3000 = 5x + 10

3000 - 10 = 5x

2990 = 5x

2990/5 = x

x = 598 books in the third pile!

We can check that:

3000 = 2*598 + 10 + 2*598 + 598

3000 = 1196 + 10 + 1196 + 598

3000 = 3000 CHECK!

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There are (n r) different linear arrangements of n balls of which r are black and n-r are white. give a combinatorial explanatio

Vanyuwa [196]

Answer:

$\frac{n!}{r!(n-r)!}$

Step-by-step explanation:

Combinatorial explanation:

The n balls have to be arranged in n positions and the only distinction is where are the black and where white balls are.

We can choose the position of black balls in $\binom{n}{r}$ ways, therefore, white ones are on the remaining positions.

Using binomial we can have explanation written below:

The balls can be arranged in n! possible permutations.

To be precise one particular arrangement includes $r!(n-r)!$ permutations. Since r black balls can be permuted in r! ways and white balls in (n-r)! different orders.