The consumption of electricity, in units, for 20 customers in a locality is…

Step-by-Step Solution

To find the mean of grouped data, use the formula: Mean = (Σfx) / Σf, where 'f' is the frequency (number of customers) and 'x' is the data value (consumption in units).

1. Calculate the product of each consumption unit (x) and its frequency (f):

   • 20 units * 4 customers = 80

   • 25 units * 4 customers = 100

   • 30 units * 7 customers = 210

   • 35 units * 3 customers = 105

   • 40 units * 2 customers = 80

2. Find the sum of these products (Σfx):

   • 80 + 100 + 210 + 105 + 80 = 575

3. Find the sum of frequencies (Σf):

   • 4 + 4 + 7 + 3 + 2 = 20

4. Calculate the Mean:

   • Mean = 575 / 20 = 28.75 units.