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Matt71
Group Title
An athlete's usual running speed in still air is 8 m/s.
On one windy day, the time he took to run 100m, running with the wind, was 6 2/3 seconds less than the time he took to run 100m, running against the wind.
a. Given that the speed of the wind that day was "w m/s", write down an expression in terms of w for the time he took to run 100m when running with the wind.
b. Form an equation in w and show that it reduces to w^2+30w64=0
c. Solve the equation to find the speed of the wind
 2 years ago
 2 years ago
Matt71 Group Title
An athlete's usual running speed in still air is 8 m/s. On one windy day, the time he took to run 100m, running with the wind, was 6 2/3 seconds less than the time he took to run 100m, running against the wind. a. Given that the speed of the wind that day was "w m/s", write down an expression in terms of w for the time he took to run 100m when running with the wind. b. Form an equation in w and show that it reduces to w^2+30w64=0 c. Solve the equation to find the speed of the wind
 2 years ago
 2 years ago

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thewildones Group TitleBest ResponseYou've already chosen the best response.0
i say b..
 2 years ago

Matt71 Group TitleBest ResponseYou've already chosen the best response.0
Ummm... It's not a multiple choice question, those are actually the questions, you know, a,b and c
 2 years ago

ganeshie8 Group TitleBest ResponseYou've already chosen the best response.0
(time taken to travel against wind)  (time take to travel with wind) = 6 2/3 seconds
 2 years ago

ganeshie8 Group TitleBest ResponseYou've already chosen the best response.0
time = distance/speed
 2 years ago

ganeshie8 Group TitleBest ResponseYou've already chosen the best response.0
can you calculate both the times, and plug in ?
 2 years ago

FoolAroundMath Group TitleBest ResponseYou've already chosen the best response.2
Speed of the man running with the wind = (8+w) Speed when running against the wind = (8w) Time taken for 100m running with the wind = 100/(8+w) Time taken for 100m running against the wind = 100/(8w) Given: \[\frac{100}{8+w} = \frac{100}{8w}  6\frac{2}{3}\] Can you proceed further ?
 2 years ago

matricked Group TitleBest ResponseYou've already chosen the best response.0
the equation can be deduced from ((100/(8w))  ((100/(8+w)) =20/3 which reduces to 2w/((8w)(8+w)) =1/15 and hence w^2+30w64=0 solving we have (w+32)(w2)=0 w=2 (w=32 ignored) spped of wind =2m/s
 2 years ago
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