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3.2 Samples of aluminum-alloy channels were tested for stiffness. The following frequency distribution was obtained. The distribution is assumed to be normal Stiffness Frequency 2480 2440 35 2400 2360 33 2320 21 What is the approximate mean of the population from which the samples were taken? (a) 2367 (b) 2398 (c) 2402 (d) 2419

User KyleLanser
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6 votes

Answer:

Option c - 2402

Explanation:

Given : Samples of aluminum-alloy channels were tested for stiffness. The following frequency distribution was obtained.

To find : What is the approximate mean of the population from which the samples were taken?

Solution :

The distribution is assumed to be normal as

Stiffness(x) Frequency(f)
x* f

2480 23
2480* 23=57040

2440 35
2440* 35=85400

2400 40
2400* 40=96000

2360 33
2360* 33=77880

2320 21
2320* 21=48720

Total = 152 =365040

The mean of the data is given by,


\text{Mean}=(\sum xf)/(\sum f)


\text{Mean}=(365040)/(152)


\text{Mean}=2401.578

Approximately, the approximate mean of the population from which the samples were taken is 2402.

Therefore, option c is correct.

User All Jazz
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