Provide at least three reasons why friction is needed.

Sample Response: Friction allows people and objects to move. It provides traction for an object to start moving or change direction. It can also give people a better grip on objects. Finally, friction keeps objects in place when they are set down.

-Friction makes movement possible.

-Friction provides traction

-Friction makes it easier to hold on to objects

-Friction keeps objects in place.

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