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creativ13 [48]
3 years ago
11

A manufacturer of new light bulbs claims the average lifetime of its long-life bulb is more than 4000 hours. To test this claim,

a reputable testing firm took a random sample of 100 bulbs and life tested them. The testing firm found the average life of the sample to be 4500 hours with a sample standard deviation, s = 400 hours. The value of the test statistic for this problem isA 1.25B -1.25C 12.5D -12.5E None of the values listed
Mathematics
1 answer:
natka813 [3]3 years ago
5 0

Answer: C. 12.5

Step-by-step explanation:

Given : A manufacturer of new light bulbs claims the average lifetime of its long-life bulb is more than 4000 hours.

Population mean :  \mu=4000

Sample size : n= 100

Sample mean : \overline[x}=4500

Standard deviation: s=400

The value of test-statistic is given by :-

z=\dfrac{\overline{x}-\mu}{\dfrac{s}{\sqrt{n}}}\\\\\Rightarrow\ z=\dfrac{4500-4000}{\dfrac{400}{\sqrt{100}}}\\\\\Rightarrow\ z= 12.5

Hence, the value of the test statistic for this problem is 12.5.

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By selling a cow for Rs 144, there is a profit of the same percentage as its cost price. Find the cost price.​
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Answer:

Step-by-step explanation:

<h2><u>☼︎</u><u>Answer:</u></h2>

The cost price of cow = Rs.80

Explanation:

<h2><u>☼︎</u><u>Given :-</u></h2>

  • By selling a cow for Rs 144, there is a profit of the same percentage as its cost price.
<h2><u>☼︎</u><u>T</u><u>o Find</u><u>:</u><u>-</u></h2>

  • The cost price.
<h2 /><h2 /><h2><u>☼︎</u><u>L</u><u>e</u><u>t</u><u>:</u><u>-</u></h2>

  • The cost price of cow = Rs.x

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