Question

Tally Marks	Number of Observations
	________________

Answer 1

Tally mark is a way by which we can count the occurrence of any data by using a small single line to represent one occurrence of data and cutting four lines by a single line to represent a group of five occurrence.

So here there is a group of 5 and 2 more lines are there so $5+2=7$

hence the answer is $7$