1. Grouped Frequency Calculating an estimate of the mean Jill Robertson

2. Which is the modal class? Weight61 – 6566 – 7071 – 7576 –8081 - 85 Freq.92029157 71 - 75 Question 1 A gardener checks the weights (in grams) of a number of tomatoes for grading purposes. Here are her results Calculate an estimate for the mean Weight61 – 6566 – 7071 – 7576 –8081 - 85 Freq.92029157 First of all we need a representative value for each group Weight61 – 6566 – 7071 – 7576 –8081 - 85 Freq.92029157 6368737883 Mid-point

3. = m6368737883 Weight61 – 6566 – 7071 – 7576 –8081 - 85 Freq.92029157 m x f Mean = = 72.4375= 72.4 (3 sf) Now we need to calculate a total of the weight of tomatoes in each group 63 x 9 567 68 x 20 1360 73 x 29 78 x 15 83 x 7 21171170581 80 5795 We need to work out the total of our estimate of the weight and the total frequency

4. Why is this an estimate of the mean? Because the data has been grouped and so exact data has been lost

5. Calculate an estimate of the mean for this distribution Weight (Kg)0-1010-2020-3030-4040-5050-60 Frequency1118161152 Wt (Kg)0-1010-2020-3030-4040-5050-60 F1118161152 515253545 Mid-point 55 63 1445 5 x 1115 x 1825 x 1635 x 1145 x 555 x 2 55270400385225110 Mean = = 22.9365..= 22.9 (3 sf) m x f