Deconstructing the QuestionThis problem describes two drivers covering the
same distance (from the passing point to the destination), but in different amounts of time.
When distance is constant, Speed and Time are
inversely proportional.
- Passing Point Time: 1:20 pm
- Albert's Speed (\(R_A\)): 60 mph
- Goal: Find Beatrice's Speed (\(R_B\)).
Step 1: Calculate the Time taken for the remaining tripWe only care about the segment from the passing point (1:20 pm) to Megiddo.
Beatrice's Time (\(T_B\)):Starts at 1:20 pm, arrives at 3:20 pm.
\(T_B = 2 \text{ hours} = 120 \text{ minutes}\)
Albert's Time (\(T_A\)):Starts at 1:20 pm (the moment he is passed), arrives at 4:10 pm.
\(T_A = 2 \text{ hours } 50 \text{ minutes} = 120 + 50 = 170 \text{ minutes}\)
Step 2: Use the Inverse Ratio FormulaSince Distance is constant:
\(\frac{R_B}{R_A} = \frac{T_A}{T_B}\)
Substitute the known values:
\(\frac{R_B}{60} = \frac{170}{120}\)
Step 3: Solve for Beatrice's SpeedSimplify the fraction:
\(\frac{R_B}{60} = \frac{17}{12}\)
Multiply by 60:
\(R_B = 60 \times \frac{17}{12}\)
\(R_B = 5 \times 17\)
\(R_B = 85 \text{ mph}\)
Answer: B