Answer: 1. 41.67years
2. £9.21
3. 7.75cm
Step-by-step explanation:
1. At a party, thirty people have an age of 30, forty have an age of 40 and fifty an age of fifty. What is their average age?
Total ages = (30 × 30) + (40 × 40) + (50 × 50) = 900 + 1600 + 2500 = 5000
Total number of people = 30 + 40 + 50 = 120
Average age = Total ages / Total number of people
= 5000/120
= 41.67 years
2. In a hardware shop, there are 30 spanners costing £6, 55 hacksaws costings £9 and 10 soldering irons costings £20. What is the average cost per item?
Total cost of items = (30 × £6) + (55 × £9) + (10 × £20) = £180 + £495 + £200 = £875
Total number of items = 30 + 55 + 10 = 95
Average cost per item = £875/95 = £9.21
3. Using this frequency table, find the average height of a turnip.
Height (to nearest cm)
6cm 7cm 8cm 9cm 10cm
Frequency: 3 8 12 4 1
Total height = (3 × 6cm) + (8 × 7cm) + (12 × 8cm) + (4 × 9cm) + (1 × 10cm) = 18cm + 57cm + 96cm + 36cm + 10cm = 217cm
Total number of turnips = 3 + 8 + 12 + 4 + 1 = 28
Average height = 217cm/28 = 7.75cm
