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Mariulka [41]
3 years ago
5

A large city newspaper periodically reports the mean cost of dinner for two people at restaurants in the city. The newspaper sta

ff will collect data from a random sample of restaurants in the city and estimate the mean price using a 90 percent confidence interval. In past years, the standard deviation has always been very close to $35. Assuming that the population standard deviation is $35, which of the following is the minimum sample size needed to obtain a margin of error of no more than $5 ?A) 90
B) 112
C) 133
D)147
Mathematics
1 answer:
inysia [295]3 years ago
6 0

Answer: C) 133

Step-by-step explanation:

The formula to find the sample size is given by :-

n=(\dfrac{z^*\cdot\sigma}{E})^2

, where z* = Critical z-value

\sigma = Population standard deviation for prior study.

E= Margin of error.

As per given , we have

\sigma=$35

E= 5

The critical z-value for 90% confidence level is 1.645.

Substitute al;l the value sin the above formula  , we get

n=(\dfrac{1.645\times 35}{5})^2

n=(\dfrac{57.575}{5})^2

n=(11.515)^2

n=132.595225\approx133

Hence, the minimum sample size needed is 133.

Thus , the correct answer is : C) 133

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The sum of an arithmeit cprogression consisting of 20 positive integer terms with positive common difference is equal to 2020. (
Rufina [12.5K]

Answer:

a) possible progressions are 5

b) the smallest and largest possible values of the first term are 16 and 82

Step-by-step explanation:

<u>Sum of terms:</u>

  • Sₙ = n/2(a₁ + aₙ) = n/2(2a₁ + (n-1)d)
  • S₂₀ = 20/2(2a₁ + 19d) = 10(2a₁ + 19d)
  • 2020 = 10(2a₁ + 19d)
  • 202 = 2a₁ + 19d

<u>In order a₁ to be an integer, d must be even number, so d = 2k</u>

  • 202 = 2a₁ + 38k
  • 101 = a₁ + 19k

<u>Possible values of k= 1,2,3,4,5</u>

  • k = 1 ⇒ a₁ = 101 - 19 = 82
  • k = 2 ⇒ a₁ = 101 - 38 = 63
  • k = 3 ⇒ a₁ = 101 - 57 = 44
  • k = 4 ⇒ a₁ = 101 - 76 = 25
  • k = 5 ⇒ a₁ = 101 - 95 = 16

<u>As per above, </u>

  • a) possible progressions are 5
  • b) the smallest and largest possible values of the first term are 16 and 82
6 0
3 years ago
Olivia went to buy shoes at the mall. The shoes cost $55. If tax was 8%, how much did Olivia pay in all? i don't understand it
Alik [6]

Answer:

$59.40

Step-by-step explanation:

8% is equal to 0.08

since you are adding the tax to the original cost you will multiply 55 by 1.08 to get the cost of the shoes plus the tax.

5 0
3 years ago
Read 2 more answers
The maximum acceptable level of a certain toxic chemical in vegetables has been set at 0.4 parts per million (ppm). A consumer h
Elodia [21]

Answer:

Null hypothesis : \mu \leq 0.4

Alternative hypothesis: \mu >0.4

And for this case a type of error I for this case would be reject the null hypothesis that the population mean is lower or equal than 0.4 when actually is true.

A Type I error would occur if, in fact, μ ≤ 0.4 ppm, but the results of the sampling lead to the conclusion that μ > 0.4 ppm

Step-by-step explanation:

Previous concepts

A hypothesis is defined as "a speculation or theory based on insufficient evidence that lends itself to further testing and experimentation. With further testing, a hypothesis can usually be proven true or false".  

The null hypothesis is defined as "a hypothesis that says there is no statistical significance between the two variables in the hypothesis. It is the hypothesis that the researcher is trying to disprove".  

The alternative hypothesis is "just the inverse, or opposite, of the null hypothesis. It is the hypothesis that researcher is trying to prove".  

Type I error, also known as a “false positive” is the error of rejecting a null  hypothesis when it is actually true. Can be interpreted as the error of no reject an  alternative hypothesis when the results can be  attributed not to the reality.  

Type II error, also known as a "false negative" is the error of not rejecting a null  hypothesis when the alternative hypothesis is the true. Can be interpreted as the error of failing to accept an alternative hypothesis when we don't have enough statistical power

Solution to the problem

For this case we are trying to check the following hypothesis:

Null hypothesis : \mu \leq 0.4

Alternative hypothesis: \mu >0.4

And for this case a type of error I for this case would be reject the null hypothesis that the population mean is lower or equal than 0.4 when actually is true.

A Type I error would occur if, in fact, μ ≤ 0.4 ppm, but the results of the sampling lead to the conclusion that μ > 0.4 ppm

7 0
3 years ago
The sum of two numbers is five. the sum of the squares of the two numbers is thirteen. find the two numbers.
Sonbull [250]
2 and 3
2+3=5
2^2+3^2=13
4 0
2 years ago
random question if where humans dose that mean were a creature to bugs so confuse someone help the will get brainlist
kondaur [170]
In theory, any living organism is a creature because it needs the same basic things to live. so yes, I think us humans are a creature to bugs.
6 0
3 years ago
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