While rate of change is often used to determine the steepness of a straight line, this formula may also be utilized to measure changes in other things. Density Conversions (multiple step problems) Problem 2: Geologists' observations suggest that the two most common rocks exposed at the surface of the Earth are granite (continental crust) and basalt (oceanic crust).
To make the recipe with 8 cups of flour, how much sugar should be used?
We'll see a few examples below; but first, let me show where this formula comes from.
We started the problem with the following assumptions.
There are two workers (pipes, machines, etc), A and B.
Worker A can finish a job in X hours when working alone; Worker B can finish the same job in Y hours when working alone.
Worker A can finish a job in X hours when working alone.
Worker B can finish a job in Y hours when working alone The number of hours they need to complete the jobwhen they're both working at the same time is given by Once you're "armed" with this formula, solving these problems will be very easy.
Since painter B is twice as fast, he would need 15 hours if worked alone. A 10,000 litre pool is filled by two pipes: A and B. When pipe A and B are both on, they can fill this pool in 4 hours. Notice that there is an important difference between the wording of this problem and the other two.
In this case, we're given the rate of work of pipe A rather than the time it needs to complete an activity.