Is 9.42 a rational number

Ronnie wants to lower his utility bills to save money on his monthly expenses. He discovers that if he replaces his water heater

Soloha48 [4]

Alright, lets get started.

Last year, Ronnie's utility expenses were = 1935.67 $

After switching to electric water heater to solar water heater, his yearly utility bills get reduced.

This year, Ronnie's utility expenses are = 862.40 $

So the difference on utility bills Ronnie saved = $1935.67 - 862.40$

so, difference Ronnie saved = 1073.27 $

So, the percentage of amount Ronnie saved = $\frac{1073.27}{1935.67} *100$

Percentage of amount Ronnie saved = 55.45 %

Hence, 55.45 % Ronnie save on his utlility bills by switching to a solar water heater. : Answer

Hope it will help :)

5 0

2 years ago

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One morning, eight buses arrive at a bus stop.

Semenov [28]

Answer:

0 and 5 minutes

Step-by-step explanation:

Median is the middle observation of given data. It can be found by following steps:

Arranging data in ascending or descending order.

Taking the average of middle two value if the total number of observation is even, and this average is our median.

or, if we odd number of observation then the most middle value is our median.

The mode is the observation which has a high number of repetitions (frequency).

We have given 8 numbers and we have to find the other two numbers a minute late for each bus to arrive at the bus stop.

Also, we have given the median and mode of all 10 buses i.e. 3.5 and 0 respectively.

Since the mode is 0, so the frequency of 0 must be greater than 2 times and less than or equal to 4 times.

The frequency of 0 is 4 is not possible as then we didn't get a median 3.5 then.

So the frequency of 0 is 3.

Hence one of number is 0 in two unknown number of a minute late for each bus arrive at the bus stop.

Now, we have the number of minutes late for each bus after arranging them in ascending order is: 0 0 0 2 2 6 8 8 9

For getting a median 3.5 we must have a number between 2 and 6. Let it be x then:

$\frac{2+x}{2} = 3.5$

⇒x = 5

Hence the number of minutes late for each bus is: 0 0 0 2 2 5 6 8 8 9

Thus, 0 and 5 are minutes late for the two-afternoon buses.

6 0

2 years ago

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A sociologist wishes to estimate the average number of automobile thefts in a large city per day within 2 automobiles. He wishes

anzhelika [568]

Answer:

$n=(\frac{2.58(4.2)}{2})^2 =29.35 \approx 30$

So the answer for this case would be n=30 rounded up to the nearest integer

Step-by-step explanation:

Information given

$ME = 2$ the margin of error desired

$\sigma =4.2$ standard deviation from previous studies

The margin of error is given by this formula:

$ME=z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (a)

And on this case we have that ME =2 and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=(\frac{z_{\alpha/2} \sigma}{ME})^2$ (b)

The critical value for 99% of confidence interval now can be founded using the normal distribution. The significance level is $\alpha=0.01$ and the critical value would be $z_{\alpha/2}=2.58$ , replacing into formula (b) we got:

$n=(\frac{2.58(4.2)}{2})^2 =29.35 \approx 30$

So the answer for this case would be n=30 rounded up to the nearest integer

5 0

2 years ago

HELP PLS>>> The vector (3, - 7) ) is rotated by an angle of (3pi)/4 radians and then reflected across the y-axis. If th

horsena [70]

Answer:

$a \approx -2.826$ , $b \approx 7.072$

Step-by-step explanation:

First, the vector must be transformed into its polar form:

$r = \sqrt{3^{2}+ (-7)^{2}}$

$r \approx 7.616$

$\theta \approx 2\pi - \tan^{-1}\left(\frac{7}{3} \right)$

$\theta \approx 1.629\pi$

Let assume that vector is rotated counterclockwise. The new angle is:

$\theta' = \theta + \frac{3\pi}{4}$

$\theta' = 2.379\pi$

Which is coterminal with $\theta'' = 0.379\pi$ . The reflection across y-axis is:

$\theta''' = \pi - \theta''$

$\theta''' = 0.621\pi$

The equivalent vector in rectangular coordinates is:

$a = 7.616\cdot \cos 0.621\pi$

$a \approx -2.826$

$b = 7.616\cdot \sin 0.621\pi$

$b \approx 7.072$

7 0

2 years ago

The information below is the number of daily emergency service calls made by the volunteer ambulance service of Walterboro, Sout

mafiozo [28]

Answer:

Step-by-step explanation:

Hello!

The variable of interest is

X: The number of emergency service calls made by the volunteer ambulance service of Walterboro, South Carolina for 50 days.

a)

In the first column, you have the possible number of emergency calls made, in the second column, you have the observed absolute frequency (fi) for each value of the variable.

To establish the probability distribution you have to calculate the relative frequency (hi) for each value of X.

The formula for the relative frequency is

hi= fi*n where i= 0, 1, 2, 3, 4

X₁= 0

f₁= 8

h₁= 8/50= 0.16

X₂= 1

f₂= 10

h₂= 0.20

X₃= 2

f₃= 22

h₃= 22/50= 0.44

X₄= 3

f₄= 9

h₄= 9/50= 0.18

X₅= 4

f₅= 1

h₅= 1/50= 0.02

(See attachment)

b)

The variable of interest is a cuantitative discrete variable, so this is an example of a driscrete distribution.

Discrete variables are numerical and take certain numbers within its range of definition, contrary to the continuous variables that can take any value within the range of definition of the variable.

Another example of a discrete variable is "the money", If the variable is "I have at most 10 dollars in my wallet", the range of definition goes from 0 dollars to 10 dollars.

c) To calculate the mean when the data is arranged in a frequency table you have to use the following formula:

X[bar]= ∑Xihi= (0*0.16)+(1*0.2)+(2*0.44)+(3*0.18)+(4*0.02)= 1.7

This means that they expect an average of 1.7 calls per day.

d) The formula for the standard deviation is:

$S=\sqrt{\frac{1}{n-1}[sumX^2fi-\frac{(sumXfi)^2}{n} ] }$

∑X²fi= (0²*8)+(1²*10)+(2²*22)+(3²*9)+(4²*1)= 195

∑Xfi= (0*8)+(1*10)+(2*22)+(3*9)+(4*1)= 85

$S=\sqrt{\frac{1}{49}[195-\frac{(85)^2}{50} ] }= 1.015$

I hope this helps!

3 0

2 years ago