Step 1: Define variables
Let S be the speed of the slower plane.
Let F be the speed of the faster plane.
Given that the slower plane is 60 mph slower than the faster plane:
F = S + 60
Step 2: Use the given information
The slower plane takes 3 hours for the trip, so the total distance (D) is:
D = S × 3
Step 3: Analyze the statements
(1) The trip was 1,590 miles.
- Using D = 1,590, we get:
S × 3 = 1,590
S = 1,590 / 3 = 530 mph
- This allows us to determine S, so we can also find F:
F = 530 + 60 = 590 mph
- Now, time for the faster plane:
Time = Distance / Speed = 1,590 / 590 = 2.7 hours
- This statement alone is sufficient.
(2) The slower plane travels at 530 miles per hour.
- This directly gives S = 530 mph, so we can compute F:
F = 530 + 60 = 590 mph
- Since distance is S × 3 = 1,590, we already know the distance.
Time for the faster plane:
Time = 1,590 / 590 = 2.7 hours
- This statement alone is sufficient.
Step 4: Conclusion
Each statement alone is sufficient to answer the question.
Answer: D (Each statement alone is sufficient)