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3 years ago

8

PLEASE HELP WILL MARK BRAINLIEST

1 answer:

Talja [164]3 years ago

4 0

Answer: -9 for the first one -1440 i think

Step-by-step explanation:

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Trevin puts 8 gallons of gas in his car and pays $22.

Leya [2.2K]

Answer:

$2.75 a gallon

Step-by-step explanation:

22/8= 2.75

6 0

3 years ago

Read 2 more answers

Many people feel that the drying of pavement marking paint is much too slow. You spend several days looking for the fastest dryi

slavikrds [6]

Answer:

21

Step-by-step explanation:

Using<em> Simple Random Sampling</em>, we can estimate the sample size by the formula

$\bf n=\frac{Z^2S^2}{e^2}$

where

n = sample size

Z = the z-score corresponding to the confidence level 99.5%

S = the assumed standard deviation = 3 seconds

e = margin of error = 2 seconds

<em>It is worth noticing that the higher the confidence level, the larger the sample should be. </em>

The z-score corresponding to a confidence level of 99.5% can be obtained either with a table or the computer and equals

Z = 3.023

Replacing the values in our formula

$\bf n=\frac{(3.023)^23^2}{2^2}=20.5616\approx 21$

So the size of the sample should be at least 21.

7 0

3 years ago

baherus [9]

Answer: see proof below

<u>Step-by-step explanation:</u>

Given: cos 330 = $\frac{\sqrt3}{2}$

Use the Double-Angle Identity: cos 2A = 2 cos² A - 1

$\text{Scratchwork:}\quad \bigg(\dfrac{\sqrt3 + 2}{2\sqrt2}\bigg)^2 = \dfrac{2\sqrt3 + 4}{8}$

Proof LHS → RHS:

LHS cos 165

Double-Angle: cos (2 · 165) = 2 cos² 165 - 1

⇒ cos 330 = 2 cos² 165 - 1

⇒ 2 cos² 165 = cos 330 + 1

Given: $2 \cos^2 165 = \dfrac{\sqrt3}{2} + 1$

$\rightarrow 2 \cos^2 165 = \dfrac{\sqrt3}{2} + \dfrac{2}{2}$

Divide by 2: $\cos^2 165 = \dfrac{\sqrt3+2}{4}$

$\rightarrow \cos^2 165 = \bigg(\dfrac{2}{2}\bigg)\dfrac{\sqrt3+2}{4}$

$\rightarrow \cos^2 165 = \dfrac{2\sqrt3+4}{8}$

Square root: $\sqrt{\cos^2 165} = \sqrt{\dfrac{4+2\sqrt3}{8}}$

Scratchwork: $\cos^2 165 = \bigg(\dfrac{\sqrt3+1}{2\sqrt2}\bigg)^2$

$\rightarrow \cos 165 = \pm \dfrac{\sqrt3+1}{2\sqrt2}$

Since cos 165 is in the 2nd Quadrant, the sign is NEGATIVE

$\rightarrow \cos 165 = - \dfrac{\sqrt3+1}{2\sqrt2}$

LHS = RHS $\checkmark$

4 0

3 years ago

When n=343 college students are randomly selected and surveyed, it is found that x=110 own a car. Find a 99% confidence interval

Liono4ka [1.6K]

Answer:

The margin of error will be "0.65". A further explanation is provided below.

Step-by-step explanation:

The given values are:

n = 343

x = 110

At 99% confidence level,

$\alpha = 1-99$ %

$=1-0.99$

$=0.01$

then,

$\frac{\alpha}{2} =\frac{0.01}{2}$

$=0.005$

or,

$Z_{\frac{\alpha}{2} }=Z_{0.005}$

$=2.576$

Now,

The point estimate will be:

⇒ $\hat{P}=\frac{x}{n}$

⇒ $=\frac{110}{343}$

⇒ $=0.321$

or,

⇒ $1-\hat{P}=1-0.321$

⇒ $=0.679$

The margin of error will be:

⇒ $E=Z_{\frac{\alpha}{2} }\times \sqrt (\frac{(\hat{P}\times (1 - \hat{P})) }{n} )$

On substituting the above values, we get

⇒ $=2.576\times \sqrt{\frac{0.321\times 0.679}{343} }$

⇒ $=2.576\times \sqrt{\frac{0.217959}{343} }$

⇒ $=0.065$

hence,

⇒ $\hat{P}-E$

⇒ $0.321-0.065$

⇒ $0.256,0.386$

6 0

3 years ago

One day, a person went to a horse racing area. Instead of counting the number of humans an horses, he conuted 74 heads and 196 l

Lina20 [59]

50 people 24 horses

8 0

3 years ago