Question

On 1st day of January, Madhulika decides to save Rs. 5,on2nd day Rs 7, on 3rd day Rs. 9. If she decides to save like this. then on 31st January what Wii be her total saving?​

Answer 1

Answer:

Rs. 1085

Step-by-step explanation:

so 1st day saving a=5

2nd day saving b=7

3rd day saving c=9

&find total saving from 1st to 31 January=?

so saving are in parallel series

5,7,9.................

so a=5

d=b-a=7-5=2

and she saves money 1st to 31 January

so n=31

Total saving S=n/2[2a+(n-1)*d]

put the value of a d &n

S=31/2[2*5+(31-1)*2]

S=31/2[10+30*2]

S=31/2[10+60]

S=(31/2)*70

S=31*35

S=1085

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