Once you attempt the question then PrepInsta explanation will be displayed.

**On the first night, he drank 60ml and added 60ml water to replace it.**

Second night onwards, he drank 20ml more than the previous night. i.e., 60 + 20 = 80 ml

On third night, 80 + 20 = 100 ml

Capacity of bottle = 3L = 3000 ml

Capacity replaced is –

60 + 80 + 100 + 120 + ...... + 2980 + 3000

In the above expression 3000 is removed because on the last night he emptied the bottle without replacement.

So, the expression is –

60 + 80 + 100 + 120 + 140 + .... 2980

This is a arithmetic progression,

T_{n}= a + (n –1) d

2980 = 60 + (n –1) 20

n = 147

Total quantity is calculated by applying the sum formula

S_{n}={a+L}\times \frac{n}{2}

S_{n}={60+2980}\times \frac{147}{2}

=223440 ml

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