When not moving on the sidewalk, Maya can walk the length of the sidewalk in 7 minutes. If she stands on the sidewalk as it moves, she can travel the length in 4 minutes. If Maya walks on the sidewalk as it moves, how many minutes will it take her to travel the same distance? Assume she always walks at the same speed, and express your answer as a decimal to the nearest tenth.
(a) 3.6 (b) 2.5 (c) 3.8 (d) 2.8

• assume distance of sidewalk "x"
  speed1 (moving on sidewalk)
  speed2 (moving off sidewalk)
  since both the movements are in same direction, we can do speed1 + speed 2
  speed1 = x/4
  speed2 = x/7
  speed1 + speed2 = 11x/28 = 0.39286x
  now new time while moving on sidewalk = x/0.39286x = 2.54544
  hence, the answer is 2.5
• 10 years agoHelpfull: Yes(16) No(3)
• walk in 7 min
  as it move she can cover in 4 min as she require less time to move so we considor the respective ration.here only we have to match 4 min of moving bcs here both speed are added
  1 min speed of walk respect to move 4/7=0.57
  now as she walk on side walk as moves
  we have to considor both speed
  now we get both speed now simpli by adding get answer
  now we know that as she covers a distance in 2 min+ distance cover by walk in 2 min
  i,e 2+1.14=3.14
  now for remaining it require 0.5 min
  so by walking she cover 0.27 and moving 0.5
  so total is 4 and time is 2.5
  i think ans 2.5
• 10 years agoHelpfull: Yes(11) No(3)
• V1 be the velocity of maya = L/t1
  V2 be the velocity of sidewalk = L/t2
  as the travelling lenght is same V1t1=V2t2
  V1=V2*t2/t1
  V3(velocity when maya walks on the sidewalk) = V2+V1 = V2*(1+(t2/t1))
  V3t3=V2t2
  t3=t2/(1+(t2/t1))
  = 4/(1+(4/7))
  = 2.54
  
• 10 years agoHelpfull: Yes(7) No(0)
• b because
  7 minutes when sidewalk and maya not moving covers distance = L
  1 minute --------------------------------------------------= L/7
  4 minutes when sidewalk moving and maya not moving covers distance = L
  1 minute --------------------------------------------------= L/4
  so total moving when sidewalk is moving and maya also = L/7 + L/4 = L/(28/11)
  its mean that in 1 minute she covers L/2.5 distance so in 2.5 minute she will cover L distance.
• 10 years agoHelpfull: Yes(3) No(0)
• let Maria live x miles from the mountains
  Let her rate to mountains be y
  t=d/r
  x/y = 9
  x=9y
  Return trip 4 hours
  rate = y+40
  x/(y+40) =4
  
  substitute x
  9y/(y+40)=4
  9y=4y+160
  9y-4y=160
  5y=160
  y= 160/5
  y=32
  x=9y
  x=9*32= 288 miles
  distance to the mountain = 288 miles
  
• 10 years agoHelpfull: Yes(0) No(2)
• distance required = 1/7 + 1/4
  = (4+7)/28
  = 11/28
  = 1/2.5454 = 2.5454 min
  
• 9 years agoHelpfull: Yes(0) No(0)