Stage 9 - Q9 - 5 marks
20235
The midpoint estimate of the mean is exactly 25 minutes. Find the missing frequency in the table.
Time (min)
Frequency
\(5\le t<15\)
10
\(15\le t<25\)
?
\(25\le t<35\)
33
Hint
The unknown frequency changes the total number of observations as well as the total midpoint products.