A student digs up 8 pea plants and counts the root nodules on each…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A student digs up pea plants and counts the root nodules on each. The counts are , , , , , , and .
- What is the mean number of nodules for each plant?
- What is the median?
- How many plants have at least nodules?
Need a reminder? The key ideaShow
Rhizobium lives in the root nodules of legumes and fixes nitrogen. Azospirillum and Azotobacter are free-living nitrogen fixers. Mycorrhiza, as in Glomus, bring phosphorus from the soil. Cyanobacteria are autotrophic nitrogen fixers of paddy fields. Urea is about nitrogen by mass, so the mass of urea is the mass of nitrogen divided by .
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. Counts: .
Plan. Add for the mean, order for the median, and count for the last part.
Step 1. Mean. The total is . nodules (to one decimal place).
Step 2. Median. In order: . The middle two are and , so the median is .
Step 3. At least . The plants with and nodules, which is plants.
Answer: ; ; plants.
Check. The mean and the median are close, so no single count is far from the others.
Discussion (0)
Log in to join the discussion.
Loading…