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2 years ago

7

there are 250 people in a museum. 2/5 of the 250 people are girls. 3/10 of the 250 people are boys. the rest of the 250 people a

re adults. work out the number of adults in the museum

2 answers:

Akimi4 [234]2 years ago

7 0

His is:-

250 - 2/5 *250 - 3/10 * 250

= 250 - 100 - 75

= 250 - 175

= 75 answer

MA_775_DIABLO [31]2 years ago

3 0

He is 75, simple math shows...

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A bin of 5 transistors is known to contain 2 that are defective. The transistors are to be tested, one at a time, until the defe

xxMikexx [17]

Answer:

$P(N_1 = a , N_2 = b)= \frac{1}{5-a C 1} * \frac{5-a C 1}{5C2} = \frac{1}{5C2}=\frac{1}{10}$

Step-by-step explanation:

For the random variable $N_1$ we define the possible values for this variable on this case $[1,2,3,4,5]$ . We know that we have 2 defective transistors so then we have 5C2 (where C means combinatory) ways to select or permute the transistors in order to detect the first defective:

$5C2 = \frac{5!}{2! (5-2)!}= \frac{5*4*3!}{2! 3!}= \frac{5*4}{2*1}=10$

We want the first detective transistor on the ath place, so then the first a-1 places are non defective transistors, so then we can define the probability for the random variable $N_1$ like this:

$P(N_1 = a) = \frac{5-a C 1}{5C2}$

For the distribution of $N_2$ we need to take in count that we are finding a conditional distribution. $N_2$ given $N_1 =a$ , for this case we see that $N_2 \in [1,2,...,5-a]$ , so then exist $5-a C 1$ ways to reorder the remaining transistors. And if we want b additional steps to obtain a second defective transistor we have the following probability defined:

$P(N_2 =b | N_1 = a) = \frac{1}{5-a C 1}$

And if we want to find the joint probability we just need to do this:

$P(N_1 = a , N_2 = b) = P(N_2 = b | N_1 = a) P(N_1 =a)$

And if we multiply the probabilities founded we got:

$P(N_1 = a , N_2 = b)= \frac{1}{5-a C 1} * \frac{5-a C 1}{5C2} = \frac{1}{5C2}=\frac{1}{10}$

8 0

1 year ago

x^2+1/2x+1/16=4/9 Factor the perfect-square trinomial on the left side of the equation. (x + )² = 4/9

Nezavi [6.7K]

The missing number is the square-root of the constant term on the left-hand-side, which equals sqrt(1/16)=1/sqrt(16)=1/4.
Check:
(x+1/4)^2=x^2+2*(1/4)x+(1/4)^2=x^2+x/2+1/16. ok

Answer: x= 1/4

5 0

2 years ago

Read 2 more answers

Landon babysits and works part time at tge water park over the summer. onw week, he babysat for 3 hours and worked at the water

Tems11 [23]

B = hourly rate for babysitting and w = hourly rate for working at water park

3b + 10w = 109...multiply by -8
8b + 12w = 177...multiply by 3
----------------------
-24b - 80w = - 872 (result of multiplying by -8)
24b + 36w = 531 (result of multiplying by 3)
---------------------add
- 44w = - 341
w = -341/-44
w = 7.75 <=== hourly rate for working at water park

3b + 10w = 109
3b + 10(7.75) = 109
3b + 77.50 = 109
3b = 109 - 77.50
3b = 31.50
b = 31.50/3
b = 10.50 <== hourly rate for babysitting

8 0

1 year ago

Read 2 more answers

The state of south dakota has a population of about 814,000 people. Find the population density in people per square miles if th

Gnom [1K]

Remark

Not many per square mile. Sounds like an ideal place to live.

Step One

Find the number of Square Miles.

Area = Height * Width

Area = 380 * 200

Area = 76,000 square miles.

Step Two

Find the Density

<u>Formula</u>

Density = Population / Square Miles

Population = 814,000 people

Square miles = 76000

Solve

Density = 814000/76000 = 10.7 people per square mile.

Remark

Isn't that incredible. It means if all the Area of South Dakota were given to the people living there, each family of 4 would get roughly 1/2 a square mile.

4 0

2 years ago

N 2004, the General Social Survey (which uses a method similar to simple random sampling) asked, "Do you consider yourself athle

zmey [24]

<u>Answer-</u>

The standard error of the confidence interval is 0.63%

<u>Solution-</u>

Given,

n = 2373 (sample size)

x = 255 (number of people who bought)

The mean of the sample M will be,

$M=\frac{x}{n} =\frac{255}{2373} =0.1075$

Then the standard error SE will be,

$SE=\sqrt{\frac{M\times (1-M)}{n}}$

$SE=\sqrt{\frac{0.1075\times (1-0.1075)}{2373}}=\sqrt{\frac{0.0959}{2373}}=0.0063=0.63\%$

Therefore, the standard error of the confidence interval is 0.63%

6 0

2 years ago