how do i solve this problem ?

Question

I want to solve the problem below..

A gives B a start of 30 seconds in a km race and still beats him by 20 m. However, when he gives B a start of 35 seconds, they finish the race in a dead heat. How long does A take to run the km?

My Ans:
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Lets read the first statement:

"......A gives B a start of 30 seconds in a km race and still beats him by 20 m....."

this means , if B reaches 980 mt in t1 sec , A will reach 1000 mt in t1-35 sec.


Now lets read the next statement , it says ..

"...when he gives B a start of 35 seconds, they finish the race in a dead heat. ...."

this implies, If B reaches 1000 mt in t2 sec , then A takes t2-35 sec to cover the same 1000 mt.


so, I have got two conclusion from two statements .

now , what to do ?

Question is asking,

How long does A take to run the km?

Kindly,please DONT give me the soln .

please give me some hints so that i can solve it .

do u think , my above conclusion is correct ?

I am stuck .plz give hints

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why the speed of B is same in two cases ?

they are two different event.

speed of B may not be same in two cases

Answer 1

if t is the time A takes to run the 1000m
then
B takes t+35 to run 1000m
and
B takes t+30 to run 980m
and the velocity of B is the same in both cases

|repost|
the problem assumes that the average speed is always the same , otherwise the problem is not solvable.
velocityB = 1000/(t+35) = 980/(t+30)
solve for t gives the answer

the end
.

Answer 2

You want just a hint? That's more difficult than doing the problem for you, but I'll try.
You have two parts to the problem, right?
The first part: A gives B a 30 sec head start in a 1 km race and beats him by 20 m. What equations can you figure out here? Since you're working with distances and time you must be dealing with speed as well so d = vt. You knew that, right?
Use this formula with what you have, namely times and distance. For example lets assume it takes A T secs to finish the race. How long has B been running? What distance did he cover? What does the formula d = vt give you (say his speed = w) Call A's speed u. What does formula d = vt give you for him?
Next, B gets 35 secs lead but they finish together. What could you say about the distance B ran? and A ran? How long did it take them to run the whole 1 km?
Okay, you should have enough to do it. Need more help?
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Answer 3

Let t= time A takes to run 1000 meters
Then B runs 980 meters in t+30 seconds
and B runs 1000 meters in t+35 seconds
rate X time = distance
Since B's rate is the same both times we have:
980/(t+30) = 1000/(t+35)

Solve this one equation for t and you have A's time

Answer 4

HINT: Assume the speed of B is the same in each case.(t1 being the time it takes A to run 1000mt)

Case 1: B speed: distance/time = 980/t1+30
Case 2: B speed: distance/time = 1000/t1+35

Answer 5

ur 1st's not ', but ur 2nd is right.

this means , if B reaches 980 mt in t1 sec , A will reach 1000 mt in t1-35 sec
==> in t1-30 sec

just introduce some variables, like A n B's speeds. they will cancel out in the end somehow, so just do whatever u feel right or suitable.

Answer 6

You have a two-equation system. In your first conclusion there's a foolish error, correct it and then you have almost finished.

If i told you:

x1+x2=4
x1-3x2=-10

what would you do? Do the same for this problem.

Answer 7

problem fixing is two words, no longer a hyphenated word. Too many human beings attempt to hyphenate $#it that doesn't prefer hyphens. particular, it is human kin. having pronounced that, it is likewise English communications and workstation operations.