What is 4L 342mL+2L 214mL

The average local cell phone call length was reported to be 2.27 minutes. A random sample of 20 phone calls showed an average of

Afina-wow [57]

Answer:

Yes, at α = 0.05 it can be concluded that the average differs from the population average.

Step-by-step explanation:

We are given that the average local cell phone call length was reported to be 2.27 minutes. A random sample of 20 phone calls showed an average of 2.98 minutes in length with a standard deviation of 0.98 minutes.

Let $\mu$ = population average local cell phone call length

SO, Null Hypothesis, $H_0$ : $\mu$ = 2.27 minutes {means that the average is same as that of population average}

Alternate Hypothesis, $H_a$ : $\mu$ $\neq$ 2.27 minutes {means that the average differs from the population average}

The test statistics that will be used here is One-sample t test statistics because we don't know about population standard deviation;

T.S. = $\frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }$ ~ $t_n_-_1$

where, $\bar X$ = sample average call length = 2.98 minutes

s = sample standard deviation = 0.98 minutes

n = sample of phone calls = 20

So, test statistics = $\frac{2.98-2.27}{\frac{0.98}{\sqrt{20} } }$ ~ $t_1_9$

= 3.24

Now, at 0.05 level of significance the t table gives critical values between -2.093 and 2.093 at 19 degree of freedom for two-tailed test. Since our test statistics does not lie within these range of critical values so we have sufficient evidence to reject our null hypothesis as test statistics will fall in the rejection region.

Therefore, we conclude that the average differs from the population average.

6 0

3 years ago

Simplify these:

geniusboy [140]

First one:
Same denominator so ((9-7x)+(x-4))/(x+7)
Final answer:
(5-6x)/(x+7)

Second one:
Again same denominator so ((7x)-(11x))/(x-7)
Final answer:
(-4x)/(x-7)

Third one:
Same denominator again, ((9x)-(14x))/(x+9)
Final answer:
(-5x)/(x+9)

Fourth one:
Same denominator again, ((3x-4)-(x-9))/(x+6)
Final answer:
(2x+5)/(x+6)

Fifth one:
Different denominators here, so we have to make them them same. We do this by multiplying the first fraction by 3/3 to get (3x-9)/(2x), so ((3x-9)+(x-4))/(6x)
Final answer:
(4x-13)/(6x)

Sixth one:
This one is trickier, we have to multiply each by the others denominator, so ((11)*(x-2))/((x+9)*(x-2)) and ((3)*(x+9))/((x-2)*(x+9)) to get
(11x-22)/(x^2+7x-18) and (3x+27)/(x^2+7x-18)
Final answer:
(14x+5)/(x^2+7x-18)

Last one:
You can change the first fraction to 1/(x*(x-1)), then multiple the second fraction by (x-1)/(x-1) to get (x-1)/(x^2-x). Now add them.
Final answer:
(2-x)/(x^2-1)

Hope I helped :)

8 0

3 years ago

If x-2y=1 and 2x+3y=9 then what is x

yan [13]

The first one is x=2y plus one.
The second one is

6 0

3 years ago

Find the measure someone please help

Ierofanga [76]

Answer:

m∠B = 31°

Step-by-step explanation:

First, find the measure of angle ACB by subtracting its supplement from 180 degrees:

180 - 113 = 77

m∠ACB = 77°

Then subtract both m∠A and m∠ACB from 180 degrees, since the interior angles of a triangle always add to 180°:

m∠B = 180° - 72° - 77°

m∠B = 31°

5 0

2 years ago

The hypotenuse and one of the legs of a right triangle form an angle that has a cosine of 2 2 . what is the measure of the angle

creativ13 [48]

The correct question is
The hypotenuse and one of the legs of a right triangle form an angle that has a cosine of √2/2 .
What is the measure of the angle?

Let
∅--------> the angle
cos ∅=√2/2
cos ∅=[distance of one of the leg/hypotenuse]
[distance of one of the leg/hypotenuse]=√2/2

I could say that
distance of one of the leg=√2
and
hypotenuse=2
so
applying the Pythagorean theorem
c=hypotenuse=2
a=√2
b=?
c²=a²+b²-------> b²=c²-a²------> b²=2²-(√2)²-----> b²=2-----> b=√2

therefore
if a=b
then
the angle ∅=45°

the answer is the option
b.45 degrees

7 0

3 years ago