The rate of $90$ beats in $2$ minutes translates to a heart rate of $45$ beats per minute.

To clarify this calculation, let’s break it down step by step. We start with the information that there are $90$ beats occurring over a duration of $2$ minutes. To determine the rate per minute, we need to divide the total number of beats by the total number of minutes.

Thus, we perform the following calculation:

This result indicates that there are $45$ beats occurring each minute. This example illustrates the concept of a rate, which involves comparing two distinct quantities — in this case, the number of heartbeats to the time measured in minutes.

Understanding rates is crucial across various fields in mathematics and science. For instance, if you know a car’s speed in miles per hour, you can calculate the distance it will cover over a specific period. Similarly, knowing the rate of heartbeats per minute enables healthcare professionals to evaluate a patient’s cardiac health.

In summary, by dividing the total number of beats by the total number of minutes, we ascertain that the heart rate is $45$ beats per minute. This approach can be applied to any similar scenario where you need to calculate a rate.