Question

Maurice applied for a job and got selected. She has been offered a job with a starting monthly salary Rs.10000. If annual increment in her salary is Rs.400, form a series for her monthly salary for first six years. Is this series an AP?

• A. Rs.10000, Rs.10400, Rs.10800, Rs.11300, Rs.11600, Rs.12100, Yes
• B. Rs.10000, Rs.10400, Rs.10800, Rs.11200, Rs.11600, Rs.12000, Yes
• C. Rs.10000, Rs.10400, Rs.10800, Rs.11400, Rs.11800, Rs.12200, No
• D. Rs.10000, Rs.10400, Rs.10900, Rs.11300, Rs.11700, Rs.12100, No

Answer 1

The correct option is B

Rs.10000, Rs.10400, Rs.10800, Rs.11200, Rs.11600, Rs.12000, Yes

Annual increment in the monthly salary = Rs. 400

$2^{nd}$ year monthly salary = 10000 + 400 = Rs. 10400

$3^{rd}$ year monthly salary = 10400 + 400 = Rs. 10800

$4^{th}$ year monthly salary = 10800 + 400 = Rs. 11200

So, final series for first six month = Rs.10000, Rs.10400, Rs.10800, Rs.11200, Rs.11600, Rs.12000

Difference between first two consecutive terms = 10400 – 10000 = Rs.400

Difference between third and second consecutive terms = 10800 - 10400 = Rs.400

Difference between fourth and third consecutive terms = 11200 - 10800 = Rs.400

Since $a_2$ – $a_1$ = $a_3$ – $a_2$ = $a_4$ – $a_3$

This series is an AP