Help pls!!!!!!!!!!!!!!

Mathematics

1 answer:

kvasek [131]3 years ago

6 0

Answer:

160 for each

Step-by-step explanation:

A normal distribution means that mean = median = mode. Furthermore, in a normal distribution, 68% of values are within 1 standard deviation of the mean, 95% of values are within 2 standard deviations, and 99.7% are within 3 standard deviation.

The mean is 150 and the standard deviation is 15. 165 and 135 1 standard deviation away from the mean, so 68% of values are between 135 and 165. This means that 32% of values are not between those values. A normal distributuion is symmetric, so 16% of values are greater than 1 standard distribution and 16% are less. Therefore, 16% of values (160) are less than 135 and 16% of values (160) are greater than 165

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A 18,000 gallon swimming pool contains 7,000 gallons of water when a hose is placed into the pool and begins adding water at a r

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In 3 hours it will be 10,300 gallons of water because add 7000 + 3300 equals 10,300

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3 years ago

Suppose we want to choose 4 colors, without replacement, from 18 distinct colors.

amm1812

Answers:

(a) 73440
(b) 3060

=====================================================

Explanation for part (a)

Consider four slots labeled A,B,C,D.

We have

18 choices for slot A
17 choices for slot B
16 choices for slot C
15 choices for slot D

We started at 18 and counted down until we filled the four slots. The countdown is because we cannot repeat a color. Multiply out those values to get the answer: 18*17*16*15 = 73440

You can use the nPr permutation formula as an alternative method

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

in this case n = 18 and r = 4. The exclamation marks indicate factorial.

-----------------------------------

Explanation for part (b)

Let's say we had color labels A,B,C,... all the way up to R which is the 18th letter in the English alphabet. From those 18 letters, we can only pick four. Let's say we pick D,E,F,G.

Focusing solely on the set {D,E,F,G}, we only have one set and the order doesn't matter. So {D,E,F,G} is the same as {D,E,G,F}.

There are 4*3*2*1 = 24 ways to arrange those four items meaning that we'll need to divide the result of part (a) by 24 to get the result of part (b)

73440/24 = 3060

You could use the nCr combination formula to get the same result

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