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03/07/2021 11:50 am
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The following data gives the information on the observed lifetimes (in hours) of 225 electrical components:
Lifetime (in hours) - Frequency
0 - 20 → 10
20 - 40 → 35
40 - 60 → 52
60 - 80 → 61
80 - 100 → 38
100 - 120 → 29
Determine the modal lifetimes of the components.
1 Answer
1
03/07/2021 11:51 am
From the given data the modal class is 60 – 80.
l = 60,
The frequencies are:
fm = 61, f1 = 52, f2 = 38 and h = 20
The formula to find the mode is
Mode = l+ [(fm-f1)/(2fm-f1-f2)] × h
Substitute the values in the formula, we get
Mode = 60 + [(61-52)/(122-52-38)] × 20
Mode = 60 + ((9 x 20)/32)
Mode = 60 + (45/8) = 60 + 5.625
Therefore, modal lifetime of the components = 65.625 hours.