Answer:
I think D
Step-by-step explanation:
Answer:
0.79 ; 0.753
Step-by-step explanation:
Given that:
Students who have spent at least five hours studying GMAT review guides have a probability of 0.85 of scoring above 400 :
≥ 5 hours review = 0.85
Students who do not spend at least five hours reviewing have a probability of 0.65 of scoring above 400
< 5 hours = 0.65
70% (0.7) of business students spend atleast 5 hours review time
A.) probability of scoring above 400
(Proportion who spend atleast 5 hours review time * 0.85) + (Proportion who do not spend atleast 5 hours * 0.65)
Proportion who do not spend atleast 5 hours = (1 - proportion who spend atleast 5 hours) = 1 - 0.7 = 0.3
Hence,
P(scoring above 400) = (0.7 * 0.85) + (0.3 * 0.65) = 0.595 + 0.195
= 0.79
B.) probability that given a student scored above 400, he/she spent at least five hours reviewing for the test.
P(spent ≥5 hours review | score above 400) :
P(spent ≥5 hours review) / P(score > 400)
(0.7 * 0.85) / 0.79
0.595 / 0.79
= 0.753
The correct answer is true
Yes. Take for example a square and an ellipsis with the same perimeter. The family of ellipses with the same perimeter can have any area between that of a circle to zero (if it is extremely “thin” i.e. if its eccentricity is large). The circle has the maximum area of any other shape with the same perimeter, so the square has the same area of one of the intermediate ellipses.
