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Sladkaya [172]
2 years ago
15

Kelly runs a distance of 100 metres in a time of 10.52 seconds.

Mathematics
1 answer:
ad-work [718]2 years ago
8 0

Answer:

Upper bound for distance = 100.49. This is the highest number that you can round up to get 10.52.

Lower bound for time = 10.515 seconds. This is the lowest number that you can round up to get 10.52.

Upper bound for average speed = Upper bound for distance divided by upper bound for time.

100.49/10.5249 = 9.548 seconds.

Lower bound for average speed = Lower bound for distance divided by lower bound for time.

99.5 / 10.515 = 9.463 seconds.

Step-by-step explanation:

Hope this helps you out.

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A plot of land is about 13,000 ft by 8000 ft. Approximately how many square miles is this? Round to the nearest whole number.
Ivan
5280ft = 1mile

13,000ft = 2.46miles              8,000ft = 1.52 miles

2.46 x 1.52 = 3.7 miles^2
4 0
2 years ago
Read 2 more answers
In order to estimate the average electricity usage per month, a sample of 125 residential customers were selected, and the month
mr_godi [17]

Answer:

[895.05; 940.81]kWh

Step-by-step explanation:

Hello!

Be X: monthly electricity usage by a residential customer

X~N

σ²: 12100KWh²

To estimate the population mean using a 98% CI you have to use the following formula

[X[bar]±Z_{1-\alpha /2} * \frac{Sigma}{\sqrt{n} }]

1-α: 0.98

α0.02

α/2: 0.01

1-α/2:0.99

Z_{1-\alpha /2}= Z_{0.99}= 2.326

n= 125

X[bar]= ∑X/n= 228565/125= 917.93

[917.93±2.326 * \frac{110}{\sqrt{125} }]

[895.05; 940.81]

Using a 98% confidence level you'd expect that the interval [895.05; 940.81]kWh will include the average monthly electricity usage of residential customers.

I hope this helps!

Raw data:

Electric Usage

765

1139

714

687

1027

1109

749

799

911

631

975

717

1232

806

637

894

856

896

1272

1224

621

606

898

723

817

746

933

595

851

1027

770

685

750

1198

975

678

1050

886

826

1176

583

841

1188

692

733

791

584

1163

593

1234

603

1044

1233

1178

598

904

778

693

590

845

893

1028

975

788

1240

1253

854

1185

1164

741

1058

1053

795

1198

1240

1140

959

938

1008

1035

1085

1100

680

1006

977

1042

1252

943

1165

1014

912

791

612

935

864

953

667

1005

1063

1095

1086

810

1032

970

1099

1229

892

1074

579

754

1007

1116

583

763

1231

966

962

1132

738

1033

697

891

840

725

1031

7 0
2 years ago
During an experiment, Juan rolled a six-sided number cube 18 times. The number two occurred four times. Juan claimed the experim
natita [175]

Answer:

\frac{2}{9}

Step-by-step explanation:

Given :

Juan rolled a six-sided number cube 18 times.

The number two occurred four times.

To Find: Juan claimed the experimental probability of rolling a two was approximately 1/9. Why is Juan’s experimental probability incorrect?

Solution:

Total events = number of times cube rolled = 18

Favorable events = The number two occurred four times.  = 4

So, Experimental probability = \frac{\text{Favorable events}}{\text{Total events}}

                                               = \frac{4}{18}

                                               = \frac{2}{9}

Thus the experimental probability of rolling a two was  \frac{2}{9}

So, Juan’s experimental probability was incorrect.

3 0
2 years ago
Read 2 more answers
A recent study reported that high school students spend an average of 94 minutes per day texting. Jenna claims that the average
larisa [96]

Answer:

We have sufficient evidence to support the claim that the average for the students at Jenna's large high school is greater than 94 minutes.

Step-by-step explanation:

Jenna claims that the average time of texting at her larger high school is greater than 94 minutes per day.

From here we can see that we have to perform a hypothesis test about a sample mean. The null and alternate hypothesis will be:

Null Hypothesis: \mu \leq  94

Alternate Hypothesis: \mu > 94

Jenna collected data from a sample of 32 students. So, sample size will be:

Sample Size = n = 32

Sample Mean = x = 96.5

Sample Standard Deviation = s = 6.3

We have to perform a hypothesis test, to test Jenna's claim. Since, the value of Population Standard Deviation is unknown and the value of Sample Standard Deviation is known, we will use One Sample t-test in this case.

The formula to calculate the test statistic is:

t=\frac{x-\mu}{\frac{s}{\sqrt{n}}}

Using the values, we get:

t=\frac{96.5-94}{\frac{6.3}{\sqrt{32} } }=2.245

The degrees of freedom will be:

df = n - 1 = 32 - 1 = 31

We have to convert the t-score 2.245 with 31 degrees of freedom to its equivalent p-value. From t-table this value comes out to be:

p-value = 0.0160

The significance level is:

\alpha =0.05

Since, the p-value is lesser than the level of significance, we reject the Null Hypothesis.

Conclusion:

We have sufficient evidence to support the claim that the average for the students at Jenna's large high school is greater than 94 minutes.

3 0
2 years ago
(21.23) A study of the effect of exposure to color (red or blue) on the ability to solve puzzles used 42 subjects. Half the subj
Cloud [144]

Answer:

There is enough statistical evidence to say that the means are different.

Step-by-step explanation:

<em>The question is incomplete:</em>

<em>"The two-sample t statistic for comparing the population means has value (±0.001)."</em>

<em />

The null and alternative hypothesis are:

H_0: \mu_r-\mu_b=0\\\\H_1: \mu_r-\mu_b\neq0

The level of significance is assumed to be α=0.01.

The difference of the sample means is:

M_d=M_r-M_b=9.64-15.84=-6.20

The standard deviation for the difference of the means is:

s_d=\sqrt\frac{s_r^2+s_b^2}{n} } =\sqrt\frac{3.43^2+8.65^2}{21} }=\sqrt{\frac{85.59}{21} }=\sqrt{4.12} =2.03

Then, the t-statistic is:

t=\frac{M_d-(\mu_r-\mu_b)}{s_d} =\frac{-6.20-0}{2.03}= -3.05

The degrees of freedom are:

df=n_r+n_b-2=21+21-2=40

With 40 degrees of freedom the t-critial for a significance of α=0.01 is t=±2.705.

As the t-statistic lies in the rejection region, the effect is significant and the null hypothesis is rejected.

There is enough statistical evidence to say that the means are different.

7 0
2 years ago
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