Question

identify the dependent variable in each of the following cases by highlighting the associated part of the statement.
a) athletes who do not get enough sleep the night before will not run as fast the next day. researchers want to know if the gas mileage of cars will increase with a new type of asphalt.
b) the amount of rainfall in an area lowers the incidence of wildfires.
c) covering a scrape with a band - aide decreases healing time.
d) different rose bushes are grown in a greenhouse for two months. the number of flowers on each bush is counted at the end of the experiment.
e) you water three sunflower plants with salt water. each plant receives a different concentration of salt solutions. a fourth plant receives pure water. after a two - week period, the height is measured.
f) three redwood trees are kept at different humidity levels inside a greenhouse for 12 weeks. one tree is left outside in normal conditions. the heights of the trees are measured once a week.
g) pea plant clones are given different amounts of water for a three - week period. the first pea plant receives 400 ml of water a day. the second pea plant receives 200 ml of water a day. the third pea plant receives 100 ml of water a day. the fourth pea plant does not receive any extra water - only receiving water in natural ways. the height of the pea plants are recorded daily.
h) goldfish are fed varying amounts of food during a six - week study. one tank of goldfish is fed the normal amount of food once a day. a second tank is fed twice a day. a third tank is fed four times a day. the fishs weight is recorded daily.
i) you decide to clean the bathroom and notice the shower is covered in a strange green slime. you try to get rid of this slime with different cleaning solutions. you spray half of the shower with the leading cleaning solution and spray the other half of the shower with water. after three days of spraying equal amounts of solution three times a day, the appearance of the shower is recorded.
j) you want to test which size soccer ball is easiest to juggle with your feet. you test a size 3, size 4, and size 5 ball. you count the seconds the ball stays in the air for each of the trials. you allow yourself to use your feet and head only to juggle the ball.

Explanation:

In an experiment, the dependent variable is the variable that is being measured or observed and is affected by the independent variable.

• a) The performance of athletes (how well they run) is being measured, so the running - speed (or performance) is the dependent variable.
• b) The gas mileage of cars is what researchers want to know, so gas mileage is the dependent variable.
• c) The incidence of wildfires is being observed in relation to rainfall, so the incidence of wildfires is the dependent variable.
• d) The healing time of the scrape is being measured, so healing time is the dependent variable.
• e) The number of flowers on each bush is being counted, so the number of flowers is the dependent variable.
• f) The height of the sunflower plants is being measured, so the height of the sunflower plants is the dependent variable.
• g) The heights of the trees are being measured, so the heights of the trees is the dependent variable.
• h) The growth of pea plants (which can be measured by height or other factors) is being observed based on water amounts, so the growth of pea plants is the dependent variable.
• i) The weight of the goldfish is being recorded, so the weight of the goldfish is the dependent variable.
• j) The appearance of the shower (cleanliness or presence of slime) is being observed, so the appearance of the shower is the dependent variable.
• k) The time (seconds) it takes to juggle the ball is being counted, so the time to juggle the ball is the dependent variable.

Answer:

a) Running - speed (or performance) of athletes
b) Gas mileage of cars
c) Incidence of wildfires
d) Healing time of the scrape
e) Number of flowers on each bush
f) Height of the sunflower plants
g) Heights of the trees
h) Growth of pea plants
i) Weight of the goldfish
j) Appearance of the shower
k) Time to juggle the ball