Ram invests a total sum of 2000 rupees on government bonds in 4 years If these investments are in A ...........

Quantitative Aptitude ( CCS) Arithmetic progression

Ram invests a total sum of 2000 rupees on government bonds in 4 years. If these investments are in A.P and the sum of squares of the investments is 1200000. Find the investment made by ram in each year respectively. It is also known that he always invest more than the previous year.

200,400,600,800

875,625,375,125

125,375,625,875

50,350,650,950

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Explanation:

For solving these type of questions we must always take the numbers as
(a-3d),(a-d),(a+d),(a+3d)
So, Let the investment made by Ram in these years be (a-3d),(a-d),(a+d),(a+3d)
Then, (a-3d) + (a-d) + (a+d) +(a+3d) = 2000
=> 4a = 2000
=> a = 500
Now, again A/Q
(a-3d)² +(a-d)² +(a+d)² +(a+3d)² = 1200000
=> 4(a² + 5 d²) = 1200000
=> (a² + 5 d²) = 300000
=> 250000 + 5d² = 300000
=> 5d² = 50000
=> d² = 10000
=> d = ±100
∴ d = 100 ( As the investment increases every year so d = -100 not possible)
Hence the investments made are 200,400,600,800