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Rohan repays his total loan of ₹1,18,000 by paying every month starting with the first instalment of ₹1,000. If he increases the instalment by ₹100 every month, what amount will be paid by him in the $30^{th}$ instalment ? What amount of loan has he paid after $30^{th}$ instalment ?
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A.P formed is $1000, 1100, 1200, ...$
$a = 1000, d = 100$
$a_{30} = a + 29d = 3900$
Amount paid in $30^{th}$ instalment $= \text{\text{Rs} }3,900$
$S_{30} = \frac{30}{2}[2 \times 1000 + 29 \times 100] = 15 \times 4900 = 73,500$
$\therefore$ Total amount paid after $30^{th}$ instalment $= \text{\text{Rs} }73,500$
$a = 1000, d = 100$
$a_{30} = a + 29d = 3900$
Amount paid in $30^{th}$ instalment $= \text{\text{Rs} }3,900$
$S_{30} = \frac{30}{2}[2 \times 1000 + 29 \times 100] = 15 \times 4900 = 73,500$
$\therefore$ Total amount paid after $30^{th}$ instalment $= \text{\text{Rs} }73,500$