How can the time period of a pendulum be decreased or increased

Explanation:

The period of a simple pendulum is:

T = 2π √(L/g)

where L is the length of the pendulum and g is the acceleration due to gravity.

The period of a pendulum can be decreased by decreasing the length of the pendulum or by moving the pendulum to a place with a higher gravity.

The period of a pendulum can be increased by increasing the length of the pendulum or by moving the pendulum to a place with a lower gravity.

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form