Vanessa, a research director, is conducting an experiment to determine the effec
ID: 3171058 • Letter: V
Question
Vanessa, a research director, is conducting an experiment to determine the effectiveness of treatment for peach trees against blight. She randomly divides one grove's trees into three groups. One group is the control with no treatment for blight. She prunes the second group to remove the limbs showing blight after the spring rains. She prunes the third group as well and also sprays them with an antibiotic. Vanessa monitors the trees were monitored for five years after the start of the experiment. The following table shows the outcomes, or the counts of how long the trees in each group lived.
What is the probability that a randomly selected tree from this experiment lived two to four years or was treated with an antibiotic? Give your answer as a percentage, precise to one decimal place.
*it is not 77 neither 63
Treatment Outcomes None Pruning Antibiotic Totals 0 to 2 years 39 35 27 101 2 to 4 years 28 44 44 116 More than 4 years 13 25 51 89 Totals 80 104 122 306Explanation / Answer
P(living two to four years or was treated with an antibiotic) = P(living two to four years) + P(was treated with an antibiotic) - P(living two to four years and was treated with an antibiotic)
= 116/306 + 122/306 - 44/306
= 194/306
= 0.634
= 63.4% (ans)
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