When the total amount withdrawn is given but the date of withdrawal is not given then interest on drawings is charged for a period of:

6 months

When the total amount withdrawn is given but the dates of withdrawals are not specified, it is assumed that the amount was withdrawn evenly throughout the year. For example; Shakila withdrew Rs. 60,000 from partnership firm during the year ending March 31, 2020 and the interest on drawings is to be charged at the rate of 8 per cent per annum. For calculation of interest, the period would be taken as six months, which is the average period assuming, that amount is withdrawn evenly in the middle of the month, throughout the year. The amount of interest on drawings works out to be Rs. 2,400 as follows:
= 60000 X  6/ 12 X 8/100
= 2400