Question

Frieend please tell me the formula for this question----.

From the household expenses, A student saves rupees 5 in the first week, rupees 10 in second week, rupees 15 third week and so on. Then how much money he has saved after 15 week.

if you want to solve this question you can solve, but please write the formula in a separate box​
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Answer 1

This is the solution. Thank you. You should know the concept of Arithmetic Progression. You may however refer the solution I have shared

Answer 2

THE FORMULA IS:

s= n/2(2*a+(n-1)*d)

¶where s is { saving}

¶where n is {number of days} that is( 15) in the question

¶and a is {First Term(A.P) } that is 5 in the question

¶where d is{ Common difference} that is (10-5 =5) in question

SOLUTION:

s = n/2(2*a+(n-1)*5)

s = 15/2(2*5+(15-1)*5)

s = 15/2(10+14*5)

s = 15/2(10+70)

s = 15/2(80)

s = 15/2*80

s = 15*80/2

s = 15*40

s = 600

So the saving after 15 weeks is 600.