Question

The bottom of Ignacio's desktop is
\[74.5\,\text{cm}\] from the floor. Ignacio sits in his adjustable chair, and the tops of his legs are
\[49.3\,\text{cm}\] from the floor. Each clockwise rotation of the knob on the chair raises Ignacio's legs by
\[4.8\,\text{cm}\].
Write an inequality to determine the number of clockwise rotations,
\[r\], Ignacio could make with the knob without his legs touching the desk.

Answer 1

Let r be the number of rotations. The legs' height after r rotations is 49.3 + 4.8r, which must be less than 74.5. So
49.3 + 4.8r < 74.5.

Solve: 4.8r < 25.2 → r < 5.25. Thus he can make at most 5 full clockwise rotations without touching the desk.