Maths ·Class 9 Maths

A rally starts with 120 members. Each hour, 9 members drop out of the group. Class 9

RBSEGuide

· Jul 03, 2026 · Reviewed & updated Sep 17, 2026 · 1 min read

A rally starts with 120 members. Each hour, 9 members drop out of the group. Class 9

Question 1.

A rally starts with 120 members. Each hour, 9 members drop out of the group. How many members will remain after 1,2, 3, ... hours? Find a linear expression to represent the number of members at the end of the n^th hour. Class 9

Solution:

Initial number of members in the rally = 120

Number of members dropping out each hour = 9

Hour (n)	Number of members remaining
0	120
1	120 - 9 × 1 = 111
2	120 - 9 × 2 = 102
3	120 - 9 × 3 = 93
...	...
n	120 - 9n

∴ The linear expression to represent the number of members at the end of the nth hour is, 120 - 9n.