A geneticist is conducting research on pest-resistant walnut trees. He has developed a set of trees, when crossed, to produce offspring as follows: 40% of all trees are very resistant, 30% of trees are somewhat resistant, and 20% are susceptible to invasion by pest, for the rest, susceptibility status is undetermined. The probability of a tree from a crossing being not resistant or an unknown status is:
A)P = 0.2.
B)P = 0.3.
C)P = 0.4.
D)P = 0.5.

Question

Quizplus · Accepted Answer

From the problem, we know that 20% of the trees are susceptible to invasion by pest, and the rest have undetermined susceptibility status. This means that the remaining 80% of trees have some level of resistance.

Out of the 80%, 40% are very resistant and 30% are somewhat resistant. The remaining 10% must have an undetermined resistance status.

Therefore, the probability of a tree from a crossing being not resistant or having an unknown status is:

P = 0.2 (susceptible) + 0.1 (undetermined) = 0.3

So the best answer is B) P = 0.3.

A Geneticist Is Conducting Research on Pest-Resistant Walnut Trees