12. In a typical bike rally, every bike has to reach a speed of 20 m/min within a minute and it increase its speed by 20 m/min and the sum was 1600 m/min. Four minutes later, a new biker started running in the race. After another two minutes, the biker with the speed of 400 m/min stopped due to injuries and again two new bikers started running in the race. What is the current average speed?
A. 260 m/min
B. 220 m/min
C. 280 m/min
D. 290 m/min

• just think 1600m/min as 160 m/min and 400m/min as 40m/min. consider first speed as 160 m/min. then after 4 min add 80 m/min with 160m/min. because each min will be increased by 20m/min. so now the total will be 240 m/min. after 2 minutes a biker with 40 m/min stopped so we have to subtract this 40 from 240. but in this 2 minutes 40m/min will be increased so speed will be again 240. but after 2 others are joined add their spped also which wiil be 40m/min . so it will be 240+40= 280 m/min
• 8 years agoHelpfull: Yes(13) No(4)
• c) 280m/min
  
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• Please Explain properly friend
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• Can I get a clear explanation....?
  
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• Explain with solution ritika
  
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• can you please explain it clearly?
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• Are bawri tared
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• 220 m/min
  let total no of bikes be x
  1600 +20*4*x +(x+1)*20*2 - 400 +x*20*2 = 1240 +140*x
  dividing this by x we get average speed
  1240/x + 140
  now checking with options we get x integer only in option B
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• give me detail explanation
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