On a certain day, the rate of change of biscuits in a jar was −3 per hour. How long did it take the number of biscuits to reduce by 33?
On a certain day, the rate of change of biscuits in a jar was negative three per hour. How long did it take the number of biscuits to reduce by 33?
We are told that the rate of change of biscuits is negative three per hour. This value is negative as it is the rate of consumption of biscuits. Three biscuits are being consumed or eaten per hour. This means as time increases, the number of biscuits in the jar will decrease. This means we can calculate the time taken by dividing the change in the number of biscuits by the rate per hour.
We are told that the number of biscuits has reduced by 33. Therefore, the change in biscuits is negative 33. The rate per hour was negative three. We need to divide negative 33 by negative three. When dividing a negative number by a negative number, we get a positive answer. So negative 33 divided by negative three is 11. We can therefore conclude that it would take 11 hours for the number of biscuits in the jar to reduce by 33.