If the number of cigarettes smoked increases, then the risk for lung cancer increases. Independent variable: Dependent variable: If the number of sharks swimming in a coastal region increases, then the number of shark attacks on humans will also increase. Independent variable: Dependent variable: If the amount of milk a person drinks increases, the strength of his or her bones will stay the same. Independent variable: Dependent variable: Part B: Heart Rate Your heart rate can be determined by counting the number of times your heart beats per minute. There are several places you can find your pulse—the rhythmic pressure wave of blood in the arteries. The radial pulse can be found by placing two fingers just below the wrist creases at the base of the thumb. Another common place to feel the pulse is the carotid artery in the neck. Place two fingers, index and middle, between the trachea and large neck muscle. Be sure to sit still without talking, and slowly move the fingers together until you can feel the blood flow. In this experiment, you’re collecting data to determine how holding your breath affects your heart rate. Write a hypothesis stating whether your heart rate will increase, decrease, or stay the same after holding your breath for 30 seconds. Also, identify the independent and dependent variables. Hypothesis: Independent variable: Dependent variable: Remember, the hypothesis is a prediction based on observations and past knowledge. For more information on forming hypotheses, refer in your Lab Manual to Appendix A: How to Form a Hypothesis. Data Create a chart like the one below. Then, complete the following steps. Find your pulse. Count the number of times your heart beats in 60 seconds. Record and repeat two more times. It’s important to have more than one trial in an experiment to reduce errors. Calculate the average of the three trials, and record the results. The average can be calculated by adding the three trial values toget