Question

The following table shows the electricity (in units) used by 25 families of Eklara village in a month of May. Complete the table and answer the following questions.

Electricity used (units) `bb(x_i)`	No. of Families (frequency) `bb(f_i)`	`bb(f_ix_i)`
30	7	_________
45	2	__________
60	8	__________
75	5	__________
90	3	__________
	N = _________	`sum f_ix_i` = ______

1. How many families use 45 units electricity?
2. State the score, the frequency of which is 5.
3. Find N, and `sum f_ix_i`
4. Find the mean of electricity used by each family in the month of May.

Answer 1

Electricity used (units) `bb(x_i)`	No. of Families (frequency) `bb(f_i)`	`bb(f_ix_i)`
30	7	30 × 7 =  210
45	2	45 × 2 =  90
60	8	60 × 8 =  480
75	5	75 × 5 =  375
90	3	90 × 3 =  270
	N =  25	`sum f_ix_i` =  1425

(1) 2 families use 45 units of electricity.

(2) The score with a frequency of 5 is 75 units.

(3) N = 25, and `sum f_ix_i`= 1425

(4) Since,
Mean=`(sum f_ix_i)/"N"`

          = `1425/25`

          = 57

So, the mean of electricity used by each family in the month of May is 57.