❓Question:
A man travelled from one city to another.
What is the
distance between the two cities?
🔹 Statement (1):
He travelled the
first 1/4 of his distance at
15 mph, and the remaining
3/4 at
20 mph.
🧠 Let's define total distance =
DThen:
- Time at 15 mph = (1/4)D ÷ 15 = D/60
- Time at 20 mph = (3/4)D ÷ 20 = (3D)/(80)
BUT ⛔ There’s
no total time given, so we can’t compute
D.
We only have proportions and speeds, no actual time or distance value. 😐
👉
Statement (1) is NOT sufficient ❌
🔹 Statement (2):
The time at 20 mph was
5 hours more than the time at 15 mph.
Let’s assign variables again:
- Let time at 15 mph = t
- Then time at 20 mph = t + 5
Now we know the
difference in time, but NOT the distance he covered in each segment ❌
We
don’t know the proportion of the journey at each speed (that was in Statement 1!).
So with just this, too many unknowns.
👉
Statement (2) is NOT sufficient ❌
🔹 Combine (1) and (2):
From (1):
- First 1/4 of D at 15 mph → time = D/60
- Remaining 3/4 of D at 20 mph → time = (3D)/80
From (2):
Time at 20 mph is 5 hours
more than at 15 mph:
So:
(3D)/80 = D/60 + 5
Now we solve:
Multiply all terms by 240 to eliminate denominators:
(3D/80) * 240 = (D/60) * 240 + 5 * 240
→ 9D = 4D + 1200
→ 5D = 1200
→
D = 240 miles🎉 BOOM! We got the distance! ✅
👉
Statements (1) and (2) TOGETHER are sufficient✅ Final Answer:
c. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient. 🎯💯
📌 Summary:
- Statement 1 ❌: Gives speeds and distance ratios, but no time.
- Statement 2 ❌: Gives time difference, but no segment breakdown.
- Combined ✅: Allows us to form and solve an equation!
💡 Quick Tip:
In rate/time/distance problems, always define variables and remember:
Distance = Speed × TimeWatch out for proportions, time differences, and units! 🕒📏
Bunuel
A man travelled from one city to another. What is the distance between the two cities?
(1) He travelled the first 1/4 of his distance at a uniform speed of 15 miles per hour. Thereafter, he increased his speed to 20 miles per hour.
(2) The time for which he travelled at 20 miles per hour was 5 hours greater than the time for which he travelled at 15 miles per hour.