Question 1: A retailer recorded the weekly sales (in units) of a product over 6 weeks as follows: 120, 135, 150, 145, 130, 125. Calculate the mean weekly sales.

Answer: 132.5

Question 2: A company categorizes its customer income levels into groups with the following frequencies: £20k-£30k: 40, £30k-£40k: 60, £40k-£50k: 50. The midpoints are £25k, £35k, and £45k respectively. Find the estimated average income.

Answer: 35

Question 3: A business recorded the number of customer complaints per day over a week as: 3, 5, 2, 4, 6, 3, 4. Using midpoints for grouped data: 1, 2, 3, 4, 5, 6, calculate the estimated mean complaints per day.

Answer: 3.57

Question 4: A financial analyst groups daily stock returns into classes with frequencies: -3% to -1%: 5, -1% to 1%: 15, 1% to 3%: 10. The midpoints are -2%, 0%, and 2%. Calculate the estimated average return.

Answer: 0.56

Question 5: A business surveys its employees about hours worked per week, with data grouped as: 35-40 hours: 20, 41-45 hours: 25, 46-50 hours: 15. Calculate the estimated mean hours worked.

Answer: 43.75

Question 6: In a survey of monthly expenditure, the following grouped data was recorded: £100-£200: 50, £200-£300: 70, £300-£400: 40. Use midpoints to estimate the average expenditure.

Answer: 250

Question 7: A company's quarterly revenue (in thousands of pounds) is grouped as follows: 200-250: 3 quarters, 251-300: 4 quarters, 301-350: 2 quarters. Using midpoints, find the estimated average quarterly revenue.

Answer: 265.71

Question 8: A small business categorizes its monthly sales figures into ranges with associated frequencies: £0-£500: 10, £500-£1000: 15, £1000-£1500: 8. Calculate the estimated mean monthly sales.

Answer: 950

Question 9: A factory records the number of defective items per batch over 8 batches: 2, 3, 1, 4, 2, 3, 2, 5. Calculate the estimated mean number of defects per batch.

Answer: 2.5

Question 10: A business analyzes its weekly sales data grouped into: 100-200 units, 200-300 units, 300-400 units with respective frequencies 12, 15, 8. Using midpoints, find the estimated average weekly sales.

Answer: 238.33

Question 11: Identify and correct the mistake in this calculation of the estimated mean: Frequencies are 10, 20, 30; midpoints are 5, 15, 25; total Σfx is 700; estimated mean is 700/60.

Answer: The mistake is dividing by 60 instead of 60 (sum of frequencies), which is correct, so the estimated mean is 700/60=11.67. If the incorrect total was used, the correction is needed.