Evaluate the following expression: 3(1,-1)

Evaluate 10.2x + 9.4y when x = 2 and y = 3.

IrinaK [193]

Answer:

48.6

Step-by-step explanation:

Substitute 2 for x and 3 for y

Multiply

Simplify by rounding then add to arrive at

Answer

7 0

3 years ago

A company with a large fleet of cars wants to study the gasoline usage. They check the gasoline usage for 50 company trips chose

Nookie1986 [14]

Answer:

The 95% confidence interval is given by (25.71536 ;28.32464)

And if we need to round we can use the following excel code:

round(lower,2)

[1] 25.72

round(upper,2)

[1] 28.32

And the interval would be (25.72; 28.32)

Step-by-step explanation:

Notation and definitions

n=50 represent the sample size

$\bar X= 27.2$ represent the sample mean

$s=5.83$ represent the sample standard deviation

m represent the margin of error

Confidence =88% or 0.88

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

Calculate the critical value tc

In order to find the critical value is important to mention that we don't know about the population standard deviation, so on this case we need to use the t distribution. Since our interval is at 88% of confidence, our significance level would be given by $\alpha=1-0.88=0.12$ and $\alpha/2 =0.06$ . The degrees of freedom are given by:

$df=n-1=50-1=49$

We can find the critical values in R using the following formulas:

qt(0.06,49)

[1] -1.582366

qt(1-0.06,49)

[1] 1.582366

The critical value $tc=\pm 1.582366$

Calculate the margin of error (m)

The margin of error for the sample mean is given by this formula:

$m=t_c \frac{s}{\sqrt{n}}$

$m=1.582366 \frac{5.83}{\sqrt{50}}=14.613$

With R we can do this:

m=1.582366*(5.83/sqrt(50))

m

[1] 1.304639

Calculate the confidence interval

The interval for the mean is given by this formula:

$\bar X \pm t_{c} \frac{s}{\sqrt{n}}$

And calculating the limits we got:

$27.02 - 1.582366 \frac{5.83}{\sqrt{50}}=25.715$

$27.02 + 1.582366 \frac{5.83}{\sqrt{50}}=28.325$

Using R the code is:

lower=27.02-m;lower

[1] 25.71536

upper=27.02+m;upper

[1] 28.32464

The 95% confidence interval is given by (25.71536 ;28.32464)

And if we need to round we can use the following excel code:

round(lower,2)

[1] 25.72

round(upper,2)

[1] 28.32

And the interval would be (25.72; 28.32)

6 0

3 years ago

A bakery sold 2,070 loaves of whole-wheat bread in July. In all, the bakery sold 9,000 loaves of bread that month. What percent

Crank

Answer:

2070 / 6930 = 0.2987.....x 100 = 29.87%

3 0

3 years ago

Steve must pay 28% of his salary in federal income tax. If his salary this year is $168,000, how much is his federal income tax?

Leokris [45]

Answer:

hi

Step-by-sp explanation:

3 0

3 years ago

collect data (in decibels) of 10 different things in term of loudness. Arrange the data in ascending order & find mean, medi

ss7ja [257]

Whisper-20dB
Quiet Residence-30dB
Soft stereo in Residence-40dB
Average Speech-60dB
Cafeteria-80dB
Pneumatic Jackhammer-90dB
Loud crowd noise-100dB
Accelerating Bike-100dB
Rock concert-120dB
Jet Engine (75 ft away)-140dB

(1)Mode=100dB (since 100 is occurring the maximum no. of times, i.e. it has the highest frequency of 2)
(2)Mean=sum of observations/Total number of observations
=(20+30+40+60+80+90+100+100+120+140)/10
=770/10=10dB
(3)Median= 1/2[{n/2}th observation + {(n/2)+1}th observation], where, n=total no. of observations
So, 1/2[{10/2}th observation + {(10/2)+1}th observation]
=1/2[5th observation+6th observation]
=1/2[80+90] [Because:5th observation=80dB and 6th=90dB]
=1/2(170)
=85
Therefore, median=85dB

6 0

4 years ago

Evaluate the following expression: 3(1,-1) - (4,2)