A data question with percentages in the text tests whether you can use those details with the table. Read the question, then the table's title and headings, and ask what each percentage measures. When a percentage describes growth, apply it to the increase, then add the starting count. Keep limits as ranges, so you don't turn a maximum into an exact count. A comparison is supported only if it's true for every possible count.
Hints
- Hint 1
Check what the imaging percentages measure. How do the initial and final columns let you find that amount?
- Hint 2
Work out each species' final count by applying its share to the combined increase and adding its starting 50 fronds. Keep a range or upper limit wherever the text gives one.
- Hint 3
For any comparison, test the limits of the possible final counts. Could changing a count within those limits turn the comparison around?
Step-by-step
Separate growth from final counts
Step 1Identify what the percentages describe
Each culture initially contained 50 fronds of each species, and the question asks about the end of the experiment. What do the imaging percentages describe? They give L. minor's share of the combined increase, not all final fronds, so we need to find the growth first, then add 50.
- Step 2
Calculate each combined increase
What is the combined increase under each treatment? The table's title and headings show counts for both species together, starting at 100. Subtract that starting 100: continuous red gains 260 − 100 = 160 fronds, alternating light gains 220 − 100 = 120, and continuous blue gains 180 − 100 = 80.
- Step 3
Turn the shares into final counts
Under alternating light, between 70% and 75% of 120 gives L. minor 84 to 90 new fronds, so it ends with 134 to 140. Continuous red gives it no more than 50% of 160, so it adds at most 80 and ends with at most 130. Continuous blue gives it exactly 50% of 80, so both species add 40 and end with 90. Red's 130 is an upper limit, not a fixed count.
- Step 4
Compare the limits
Which comparison stays true at the end of the experiment, even at the limits? Alternating light can't go below 134 L. minor fronds, and continuous red can't go above 130. Alternating light must have more, because its smallest possible count is 4 fronds above red's largest. Choice D.