Hey I am just like u I wasn't at school I have been waiting for 1 hour and Noone had answer me I am sad I am going to fail
The answer is letter C. Hope I helped.
These are the events in the question above:
<span>D - has disease
</span>
<span>H - healthy (does not have disease)
</span>
<span>P - tests positive </span>
<span>It is the probability that a person has the disease AND tests positive divided by the probability that the person tests positive.
</span>
Sick, + [.04*.91] = .0364
<span>Sick, - [.04*.09] = .0036 </span>
Healthy, + [.96*.04] = 0.0384
<span>Healthy, - [.96*.96] = .9216
</span>
.0364 / (.0364 + .0.0384) = 0.487
Remember that the formula for the surface area of a sphere is

. Substitute the given surface area to solve:

. Divide by 4 on both sides:

. Divide by pi on both sides:

. Square root on both sides to find the radius: