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ad-work [718]
3 years ago
15

Dan is watching the birds in his backyard he watches none of them or 45% are sparrows how many birds are in his backyard

Mathematics
1 answer:
nadezda [96]3 years ago
3 0

Answer:

If 9 of the sparrows is 45% of the birds in the backyard, 9/x = 45/100.

Cross multiply to get 9 * 100 = 45x; simplified is 900 = 45x or 20.

This means that there are 20 birds in the backyard. You can check this by dividing 9/20 which equals 45%

none??' you mean nine?

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I give you easy question for easy points. Ok? Ok. 500+5
Mashcka [7]

Answer:

THANK YOU 505

Step-by-step explanation:

4 0
3 years ago
Read 2 more answers
Let X1,X2......X7 denote a random sample from a population having mean μ and variance σ. Consider the following estimators of μ:
Viefleur [7K]

Answer:

a) In order to check if an estimator is unbiased we need to check this condition:

E(\theta) = \mu

And we can find the expected value of each estimator like this:

E(\theta_1 ) = \frac{1}{7} E(X_1 +X_2 +... +X_7) = \frac{1}{7} [E(X_1) +E(X_2) +....+E(X_7)]= \frac{1}{7} 7\mu= \mu

So then we conclude that \theta_1 is unbiased.

For the second estimator we have this:

E(\theta_2) = \frac{1}{2} [2E(X_1) -E(X_3) +E(X_5)]=\frac{1}{2} [2\mu -\mu +\mu] = \frac{1}{2} [2\mu]= \mu

And then we conclude that \theta_2 is unbiaed too.

b) For this case first we need to find the variance of each estimator:

Var(\theta_1) = \frac{1}{49} (Var(X_1) +...+Var(X_7))= \frac{1}{49} (7\sigma^2) = \frac{\sigma^2}{7}

And for the second estimator we have this:

Var(\theta_2) = \frac{1}{4} (4\sigma^2 -\sigma^2 +\sigma^2)= \frac{1}{4} (4\sigma^2)= \sigma^2

And the relative efficiency is given by:

RE= \frac{Var(\theta_1)}{Var(\theta_2)}=\frac{\frac{\sigma^2}{7}}{\sigma^2}= \frac{1}{7}

Step-by-step explanation:

For this case we assume that we have a random sample given by: X_1, X_2,....,X_7 and each X_i \sim N (\mu, \sigma)

Part a

In order to check if an estimator is unbiased we need to check this condition:

E(\theta) = \mu

And we can find the expected value of each estimator like this:

E(\theta_1 ) = \frac{1}{7} E(X_1 +X_2 +... +X_7) = \frac{1}{7} [E(X_1) +E(X_2) +....+E(X_7)]= \frac{1}{7} 7\mu= \mu

So then we conclude that \theta_1 is unbiased.

For the second estimator we have this:

E(\theta_2) = \frac{1}{2} [2E(X_1) -E(X_3) +E(X_5)]=\frac{1}{2} [2\mu -\mu +\mu] = \frac{1}{2} [2\mu]= \mu

And then we conclude that \theta_2 is unbiaed too.

Part b

For this case first we need to find the variance of each estimator:

Var(\theta_1) = \frac{1}{49} (Var(X_1) +...+Var(X_7))= \frac{1}{49} (7\sigma^2) = \frac{\sigma^2}{7}

And for the second estimator we have this:

Var(\theta_2) = \frac{1}{4} (4\sigma^2 -\sigma^2 +\sigma^2)= \frac{1}{4} (4\sigma^2)= \sigma^2

And the relative efficiency is given by:

RE= \frac{Var(\theta_1)}{Var(\theta_2)}=\frac{\frac{\sigma^2}{7}}{\sigma^2}= \frac{1}{7}

5 0
3 years ago
The anithistamine Benadryl is often prescribed for allergies. A typical dose for a 100-pound person is 25 mg every six hours. Fo
Firdavs [7]

Answer:

56 chewable tablets

280mL liquid Benadryl

Step-by-step explanation:

For the first part:

First we need to find out how many tablets of 12.5mg would we need per dose.

1 dose is 25 mg and the tablets are in 12.5 mg form.

1 dose = \dfrac{25mg}{12.5mg} = 2

That would mean you would need 2 tablets per dose.

Next you need to calculate how many times a day it needs to be taken. A day has 24 hours and it needs to be taken every 6 hours.  Just divide 24 hours by 6 hours. So that would mean that it needs to be taken 4 times a day.

Next we need to see how many times a week it should be taken and you can get that by multiplying the number of times a day by the number of days a week.

4 x 7 = 28 times

Lastly, you multiply the number of times a week by the number of tablets per dose.

28 times a week x 2 tablets = 56 tablets.

For the second part:

12.5 mg/5mL

The needed dose is 25 mg so we need to find how many mL is needed for 25 mg. 12.5mg is only have of 25 mg we need to double it to attain the correct dosage.

\dfrac{12.5mg}{5mL} x \dfrac{2}{2} = \dfrac{25mg}{10mL}

This means that for every 25 mg, you will need to give 10mL.

Again we do the same procedure as the first to decide how much liquid Benadryl you need to give in a week. We know that based on the previous that we need to administer this 28 times a week, so just multiply the number of mL per dose by the number of times per week.

10mL x 28 = 280mL

4 0
3 years ago
To rent a certain meeting room, a college charges a reservation fee of $34 and an additional fee of $9.70 per hour. The history
Flauer [41]

Answer:

t=5

Step-by-step explanation:

34+9.70t=82.50

-34 -34.00

9.70t=48.50

divide 9.70 from both sides

t=5

3 0
3 years ago
Which monomial represents the number of square units in the area of a circle whose radius is 4x^3 units?
dangina [55]

Answer:

8x^6 esa es la respuesta correcta...

6 0
3 years ago
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