Two trains, train A and train B, 20 miles apart, approach each other going 10 ki

Question

Two trains, train A and train B, 20 miles apart, approach each other going 10 kilometers per hour so that they will meet after one hour. A fly travels between them at 15 kilometers per hour. As soon as the fly touches one train, it starts flying back to the other train. At the beginning the fly starts flying from train A to train B and then from train B to train A and so on.

a.) How far does the fly fly until she touches train B for the first time

b.) How far does the fly fly until she comes back to train A for the first time.

c.) How far does the fly fly until she comes back to train A for the 10th time.

d.) How far does the fly fly until the two trains crash.

Explanation / Answer

a) time for which fly flies = 20 miles/(10+15) kmph =20/25 =.8 hr

hence distsnce travelled by fly = 0.8 *15 =12 km

b) time for which fly flies = (20-16) miles/(10+15) kmph =4/25 =.16 hr

hence distsnce travelled by fly = .16 *15 =2.4 km

c)since distance covered = 60/5^20

6.29*10^-13 kilometres (approx) using geometric progression

d) total time for crashing = 20/20 =1 hr

hence distsnce travelled by fly = 1 *15 =15 km

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.