A farmer grows a pest resistant crop on 20 hectares…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A farmer grows a pest resistant crop on hectares. The ordinary crop needs sprays in a season, and the resistant crop needs . One spray on one hectare costs money units. The seed of the resistant crop costs money units more for each hectare.
- What is the net saving on one hectare?
- What is the net saving on the whole field?
- What is the smallest whole number of sprays that the resistant crop must save on a hectare, for the farmer to gain any money?
Need a reminder? The key ideaShow
A genetically modified organism (GMO) is a plant, bacterium, fungus or animal whose genes have been altered by manipulation. Genetic modification has made crops tolerant to cold, drought, salt and heat. It has reduced the use of chemical pesticides and the losses after harvest. It has improved the use of minerals and raised the nutritional value of food. Money saved is the number of sprays saved times the cost of one spray, less any extra cost of seed.
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. Field: hectares. Sprays: and . One spray: money units. Extra seed: money units for each hectare.
Plan. Find the sprays saved, price them, take away the extra seed, and then multiply by the area.
Step 1. Sprays saved. sprays on each hectare.
Step 2. One hectare. money units.
Step 3. The field. money units.
Step 4. The smallest saving that pays. One saved spray is worth money units, so sprays are worth . We need , so . The smallest whole number is . Check: , which is a gain.
Answer: money units; money units; sprays.
Watch out. The prices are made up for the exercise. A real farmer must use the real prices of seed and spray.
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