Mean of Frequency Tables 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?
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?
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

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