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Alex17521 [72]
3 years ago
7

e 400 trials in which the assistant maintained a neutral expression, the driver stopped in 229 out of the 400 trials. Find a 95%

confidence interval for the proportion of drivers who would stop when a neutral expression is maintained. In the 400 trials in which the assistant smiled at the driver, the driver stopped in 277 out of the 400 trials. Find a 95% confidence interval for the proportion of drivers who would stop when the assistant is smiling. What do your results in parts (a) and (b) suggest about the effect of a smile on a driver stopping at a pedestrian crosswalk? Explain briefly. (In Chapter 23, we will consider formal methods for comparing two proportions.)
Mathematics
1 answer:
Fittoniya [83]3 years ago
6 0

Answer:

Step-by-step explanation:

n = 400

Proportion p = 229/400= 0.5725

For 95% confidence interval we use Z value as 1.96

Std error = 0.025

margin of error = 1.96*0.025

Confidence interval 95% = 0.5725±Margin of error

= (0.524, 0.621)

b) When smiled x becomes 277

p = 0.6925

Std error = 0.023

Margin of error= 1.96*0.023

Confidence interval = (0.647, 0.738)

Smiling increases the chances of stopping since mean and conidence interval bounds are showing increasing trend.

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6 0
3 years ago
8. Find an equation in standard form for the ellipse with the vertical major axis of length 16 and minor axis of length 4
MA_775_DIABLO [31]

Hello,

If center is (0,0)

x²/a²+y²/b²=1 for a half horizontal axis of a, and a half vertical axis of b

Here

a=2 ==> a²=4

b=8 ==> b²=64

\boxed{\dfrac{x^2}{4}+ \dfrac{y^2}{64}=1}\\

3 0
3 years ago
Given that y is directly proportional to x. If y = 30 and x= 5, write an equation that connects y with x.
Licemer1 [7]

Given:

y is directly proportional to x.

y=30 when x=5

To find:

The equation that connects y with x.

Solution:

It is given that, y is directly proportional to x. So,

y\propto x

y=kx                     ...(i)

Where, k is the constant of proportionality.

We have, y=30 when x=5. Substituting these values in (i), we get

30=k(5)

Divide both sides by 5.

\dfrac{30}{5}=k

6=k

Substituting k=6 in (i), we get

y=6x  

Therefore, the required equation is y=6x.

8 0
2 years ago
jason runs 440 yards in 75 seconds.At this rate how many minutes does it take him to run a mile? (1 mile = 1,760 yards)​
Zepler [3.9K]

Answer: 5 minutes

Step-by-step explanation:

We know that 1760 yards are in a mile. We can convert the given info into a proportion. 440/75 = 1760/x, where x is the number of seconds it takes to run a mile. Cross-multiply to get 440x = 75*1760. Divide both sides by 440 to get x = 75*4 = 300 seconds. The problem asks for how many minutes so you have to convert 300 seconds to minutes. To do this, we have to divide 300 by 60 to get 5 minutes.

7 0
3 years ago
Rebecca went swimming yesterday. After a while she had covered one fifth of her intended distance. After swimming six more lengt
alukav5142 [94]

Answer:

Option E.

Step-by-step explanation:

Let the intended length of Rebecca's swimming is = x units

and we assume the length of the pool = l units

Now it is given in the question that " She covers one fifth of her intended distance "

That means distance covered = \frac{x}{5}

" After swimming six more lengths of the pool she had covered one quarter of her intended distance"

So \frac{x}{5}+6(l)=\frac{x}{4}

6l=\frac{x}{4}-\frac{x}{5}

6l=\frac{x}{20}

x = 20×(6l)

x = 120l

Therefore, Rebecca has to complete 120 lengths of the pool.

Option E is the answer.

4 0
3 years ago
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