Solution:Let the monthly incomes of Raman and Raghav be Rs. 8x and Rs. 9x respectively.
Monthly expenditure of Raghav = 0.50 × 9x = Rs. 4.5x
Monthly expenditure of Raman = Rs. (4.5x - 1000)
According to question: (8x - 4.5x + 1000)/(9x - 4.5x) = 5/6
21x + 6000 = 22.5x
1.5x = 6000, x = 4000
So, the monthly incomes of Raman and Raghav are Rs. 32,000 and Rs. 36,000 respectively.
Monthly expenditure of Raghav = Monthly savings of Raghav = Rs. 18,000
Monthly expenditure of Raman = 18000 - 1000
= Rs. 17,000
Monthly savings of Raman = 32000 - 17000
= Rs. 15,000
Monthly salary of Ramesh = 32000 × 3/2
= Rs. 48,000
= Rs. 30,000
Monthly savings of Ramesh = 48000 - 30,000
= Rs. 18,000
Amount invested by Raghav = 18000 × 0.50
= Rs. 9,000
Amount received by Raghav after three years
= 9000 × (1 + 0.10)³ = 9000 × 1.331 = Rs. 11,979
Amount invested by Ramesh = 18000 × 0.40
= Rs. 7,200
Amount received by Ramesh after three years
= 7200 + 7200 × 3 × 0.13
= 7200 + 2808 = Rs. 10,008
So, the desired difference = 11979 - 10008
= Rs. 1,971