Question

Tarun earned an average of Rs. 1500 per month from January to April in a year. He earned an average of Rs. 1600 per month from May to October in that year. His earning in the month of December of that year was Rs. 300 more than his earning in the month of November of that year. His average monthly earnings for the year was Rs. 1675. Find his earnings in the month of November.

Answer 1

Jan - Apr

Average earning = 1500 per month

Let the Sum of the earning from Jan to Apr be x

x/4 = 1500 [Total no. of months from Jan - Apr = 4]

x = 1500×4

x = 6000

May - Oct

Average earning = 1600 per month

Sum of the earning from May to Oct =

x/6 = 1600

x = 9600

Earning in the Dec = ₹300 more than his earning in the Nov

Let the earning in Nov be y

earning in Dec = y + 300

Avg. Monthly earnings for the year = ₹1675.

Avg = (Sum of earning in all the 12 months)/12

(earning from Jan-Dec)/12 = 1675

(jan-Apr + May-Oct + Nov + Dec)/12 = 1675

(6000 + 9600 + y + y + 300)/12 = 1675

6000 + 9600 + y + y + 300 = 1675×12

6000 + 9600 + y + y + 300 = 20,100

15,900 + 2y = 20,100

2y = 20,100 - 15,900

2y = 4200

y = 4200/2

y = 2100

Hence, Earning in the month of November = 2100.