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3 years ago

If josh's mean score for English is 14 from the scores 10, 16, a, 8, 12 then the value of a is

Mathematics

1 answer:

levacccp [35]3 years ago

8 0

Answer:

a = 24.

Step-by-step explanation:

He has 5 scores so the total for all scores is 5*14 = 70.

So a = 70 - (10 + 16 +8 +12)

= 70 - 46

= 24.

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If the mass of a material is 44 grams and the volume of the material is 6 cm^3, what would the density of the material be?

Svetlanka [38]

Density is mass per unit volume.

For the given material that has a mass of 44 grams occupying a volume of 6 cm^3, we divide the mass by the volume, i.e.

density of material = 44 grams / 6 cm^3 = 44/6 grams/cm^3 = 7.3 g/cm^3 (to two significant figures)

4 0

3 years ago

A study of peach trees found that the average number of peaches per tree was 725. The standard deviation of the population is 70

TEA [102]

Answer:

She needs to sample 189 trees.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1 - 0.95}{2} = 0.025$

Now, we have to find z in the Ztable as such z has a pvalue of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.025 = 0.975$ , so Z = 1.96.

Now, find the margin of error M as such

$M = z\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

The standard deviation of the population is 70 peaches per tree.

This means that $\sigma = 70$

How many trees does she need to sample to obtain an average accurate to within 10 peaches per tree?

She needs to sample n trees.

n is found when M = 10. So

$M = z\frac{\sigma}{\sqrt{n}}$

$10 = 1.96\frac{70}{\sqrt{n}}$

$10\sqrt{n} = 1.96*70$

Dividing both sides by 10:

$\sqrt{n} = 1.96*7$

$(\sqrt{n})^2 = (1.96*7)^2$

$n = 188.2$

Rounding up:

She needs to sample 189 trees.

3 0

3 years ago

Simplify <br> 10g + 8g - 5g

hichkok12 [17]

Answer:

13g

Step-by-step explanation:

10g + 8g = 18g

18g - 5g = 13g

7 0

2 years ago

Read 2 more answers

Someone claims that the average amount of time that a freshman at TAMU studies is 7 hours. We think it’s higher than that and de

Stels [109]

Answer:

Test statistic t = 5.25

P-value = 0.000002 (one-tailed test)

Step-by-step explanation:

This is a hypothesis test for the population mean.

The claim is that the average amount of time that a freshman at TAMU studies is significantly higher than 7 hours.

Then, the null and alternative hypothesis are:

$H_0: \mu=7\\\\H_a:\mu> 7$

The significance level is 0.05.

The sample has a size n=49.

The sample mean is M=8.5.

As the standard deviation of the population is not known, we estimate it with the sample standard deviation, that has a value of s=√s^2=√4=2.

The estimated standard error of the mean is computed using the formula:

$s_M=\dfrac{s}{\sqrt{n}}=\dfrac{2}{\sqrt{49}}=0.29$

Then, we can calculate the t-statistic as:

$t=\dfrac{M-\mu}{s/\sqrt{n}}=\dfrac{8.5-7}{0.29}=\dfrac{1.5}{0.29}=5.25$

The degrees of freedom for this sample size are:

$df=n-1=49-1=48$

This test is a right-tailed test, with 48 degrees of freedom and t=5.25, so the P-value for this test is calculated as (using a t-table):

$\text{P-value}=P(t>5.25)=0.000002$

As the P-value (0.000002) is smaller than the significance level (0.05), the effect is significant.

The null hypothesis is rejected.

There is enough evidence to support the claim that the average amount of time that a freshman at TAMU studies is significantly higher than 7 hours.

6 0

3 years ago

A home improvement contractor is painting the walls and ceiling of a rectangular room. The volume of the room is 1584 cubic feet

liq [111]

Answer:

The room dimensions that will minimize the cost of the paint are 12 ft x 12 ft x 11 ft.

Step-by-step explanation:

We can find first the volume equation using the formula of the volume of a box.

$V= xyz$

Thus we get the constraint function

$1584 = xyz$

Then since we are asked to minimize the cost, we can write the cost function which is the area of each one of the walls and ceiling multiplied by the painting cost.

$C=0.11 xy+ 2(0.06)xz+2(0.06yz \\ C =0.11 xy+0.12xz+0.12yz$

Lagrange Multipliers to find minimum cost.

We can continue finding the partial derivatives to build the system of equations required for Lagrange Multipliers method.

$C_x=\lambda V_x \\ C_y = \lambda V_y \\ C_z = \lambda V_z$

And the constraint function

$xyz=1584$

So we get

$0.11y+0.12z=\lambda yz \\ 0.11x+0.12z=\lambda xz \\ 0.12x+0.12y=\lambda xy\\ xyz=1584$

We can multiply each side of each equation by the dimension which is missing to get the full volume on the right side.

$0.11xy+0.12xz=\lambda xyz \\ 0.11xy+0.12yz=\lambda xyz \\ 0.12xz+0.12yz=\lambda xyz$

Then we can set each the equations equal to each other, so from the first one and the second equation we get

$0.11xy+0.12xz= 0.11xy+0.12yz$

We can subtract 0.11xy from both sides.

$0.12xz=0.12yz$

And we can divide both sides by 0.12z to get

$x=y$

We can repeat the process by setting the first and third equation equal to each other.

$0.11xy+0.12xz= 0.12xz+0.12yz$

We can subtract 0.12 xz from both sides

$0.11xy=0.12yz$

And we can solve by z

$z= \cfrac{0.11x}{0.12}\\ z = \cfrac{11x}{12}$

So if we replace that as well y = x on the constraint for the volume euqation we get

$1584=x(x)\left(\cfrac{11}{12}x\right) \\ 1584=\cfrac{11}{12}x^3$

We can then solve for x

$x^3 = \cfrac{1584(12)}{11}$

And taking the cube root

$x = \sqrt[3]{\cfrac{1584(12)}{11}}$

$x = \sqrt[3]{1728}$

$x=12 ft$

So then we can use the equations we have found for y and z in terms of x

$y = x \\ y = 12 ft$

And

$z= \cfrac{11x}{12}\\z= \cfrac{11(12)}{12} \\ z=11ft$

Then the dimensions of the room that will minimize the cost are 12ft x 12 ft x 11 ft. Since you have to enter using commas you can write 12, 12, 11, please check as well if you have to insert the units that are feet for each.

5 0

3 years ago