E2020 preformance task

Solve the equation 1/2x+1/4x= 16 A. 16 B. 21.3 C. 32 D. 64

Otrada [13]

1/2+1/4= 2/4+1/4= 3/4 or .75
Then,
3/4x=16
(3/4x)4/3=(16)4/3 *multiply by the reciprocal everytime you want to isolate x with a fraction\

x= 12

5 0

3 years ago

If two variables were completely correlated, their correlation coefficient would be:

meriva

Pearson's correlation coefficient 'r' measures the degree to which two variables are correlated. The value is between -1 and 1. Negative values correspond to negative correlation (as one variable increases, the other variable decreases) whereas positive values correspond to positive correlation. The larger the absolute value of r, the closer a correlation graph resembles a set of points on the same line. Therefore, if two variables are completely correlated, the correlation value is 1 or -1, depending on whether the correlation is positive or negative.

7 0

3 years ago

One side of the triangle is 4 cm, and the sum of the other two sides is equal to a

Arlecino [84]

Answer:

A) 9 cm

Step-by-step explanation:

By the Triangle Inequality, any two sides of a triangle must be greater than the remaining side.

In order to minimize the perimeter, we will assume that 4 cm is the longest side.

Thus, the two remaining sides must be greater than 4.

Since we are given that the sum of the two remaining sides is a whole number, the smallest whole number value greater than 4 is 5.

Hence, the smallest perimeter possible 9 cm.

Our answer is A.

8 0

2 years ago

Read 2 more answers

6/5 sums in simplest form

m_a_m_a [10]

Answer:

1.2 or 1 1/5

Step-by-step explanation:

To get the answer you have to divide 6/5. Once, I divide I should get 1.2 then you can keep it as a decimal (1.2) or a whole number fraction (1 1/5).

Therefore, your answers will be 1.2 or 1 1/5 (One and one fifths)

Hop this helps.

Is this incorrect? Say so in comments. Questions? Say so in comments.

6 0

3 years ago

Read 2 more answers

Allen�s hummingbird (Selasphorus sasin ) has been studied by zoologist Bill Alther A small group of 15 Allen� s hummingbirds has

Bogdan [553]

Answer:

1) 80% CI: [3.04; 3.26]gr

d= 0.11

2) n= 28 hummingbirds

Step-by-step explanation:

Hello!

The study variable of this experiment is:

X: the weight of a hummingbird. (gr)

And it has a normal distribution, symbolically: X~N(μ;σ²)

And (I hope I got it correctly) its population standard deviation is σ= 0.33

There was a sample of n= 15 hummingbirds taken, its sample mean X[bar]= 3.15 gr

1) You need to construct an 80% Confidence Interval for the population mean of the hummingbird's weight.

Since the study variable has a normal distribution, you can use either the standard normal distribution or the Student's t distribution. Both are useful to estimate the population mean. Since the population standard variance is known, the best choice is the Standard normal.

Z= X[bar] - μ ~ N(0;1)

σ/√n

The formula for the interval is:

X[bar] ± $Z_{1- \alpha /2}$ * (σ/√n)

$Z_{1- \alpha /2}= Z_{0.90} = 1.28$

3.15 ± 1.28 * (0.33/√15)

[3.04; 3.26]gr

The margin of error (d) of a confidence interval is hal its amplitude (a)

a= Upper bond - Lower bond

d= (Upper bond - Lower bond)/2

d= $\frac{(3.26-3.04)}{2}$ = 0.11

2) You need to calculate a sample size for a 80% Confidence interval for the average weight of the hummingbirds with a margin of error of d= 0.08

As I said before, the margin of error is half the amplitude of the interval, the formula you use to estimate the population mean has the following structure:

"point estamator" ± "margin of error"

Then the margin of error is:

d= $Z_{1- \alpha /2}$ * (σ/√n)

Now what you have to do is rewrite the formula based on the sample size

d= $Z_{1- \alpha /2}$ * (σ/√n)

$\frac{d}{Z_{1- \alpha /2}}$ = σ/√n

√n * $\frac{d}{Z_{1- \alpha /2}}$ = σ

√n = σ * $\frac{Z_1- \alpha /2}{d}$

n = (σ * $\frac{Z_1- \alpha /2}{d}$ )²

n= (0.33 * $\frac{1.28}{0.08}$ )²

n= 27.8784 ≅ 28 hummingbirds.

I hope it helps!

4 0

3 years ago