Question

Please help me i need it

Answer 1

To work out the estimate mean from a grouped frequency table, you:

• Work out the midpoints of each of the time ranges (this is already done for you in the 3rd column)
• You multiply the midpoints by the each of the frequencies (this is already done for you in the last column)
• Then to get the estimate mean, you add up all of values in the last row, and divided it by the sum of all the frequencies

Sum of all of the Frequency times Midpoints Column  (4th column):

280 + 420 + 480 + 700 + 1440 = 3320

Sum of all the Frequency column:

7 + 7 + 6 + 7 + 12 = 39

So

$EstimateMean=\frac{3320}{39}=85.128205..$

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Answer:

Estimate mean to 2 decimal places is: 85.13 seconds