Far Away From School

Algebra Level 2

Paul's dad was inquiring about his walk to school. Paul replied:

"If I walk 5 miles per hour, I will arrive 10 minutes early. But if I walk 4 miles per hour, I will arrive 5 minutes late."

What is the distance from the Paul's house to the school in miles?


The answer is 5.

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15 solutions

Azeem King
Apr 29, 2014

Let time be 'x'.. First case: Eq: speed=dist/time..... 5=d/x-10 Second case: 4=d/x+5 Domt forget to.convert minutes to hours..... Find d.

To solve this problem lets do distance=(distance1 - distance2) divided by (time1- time2)

Rafael Oliveira - 7 years, 1 month ago
Rahma Anggraeni
May 3, 2014

We count the time in minute and the distance is the same, so..

s = s s=s

5 × ( t 10 ) = 4 × ( t + 5 ) 5 \times (t-10) = 4 \times (t+5)

5 t 50 = 4 t + 20 5t-50 = 4t+20

t = 70 m i n u t e s t=70 minutes

Then the distance..

s = v × t s=v \times t

s = 5 × ( 70 10 ) s=5 \times (70-10)

s = 5 × 60 s=5 \times 60

Change the time into hour..

s = 5 × 1 s=5 \times 1

s = 5 m i l e s s= \boxed {5 miles}

Manish Mayank
May 3, 2014

he is saying that the difference in time will be 15 min or 1/4 hr so let the distance be n miles now, n/4 - n/5 = 1/4 or n=5 miles

X is the time remaining until the start of class, where you will not be late or early arriving at this time. This is measured in hours. The minutes early or late must be converted.

10 minutes are 0,16666... hours 5 minutes are 0,0833... hours

We have:

5 5 is to x 0.1666... x-0.1666...

4 4 is to x + 0.08333... x+0.08333...

But the time and the speed are inversely proportional.

Now we have:

5 5 is to x + 0.08333... x+0.08333... 4 4 is to x 0.1666... x-0.1666...

Making a cross multiplication

4 x + 0 , 333... = 5 x 0 , 8333... 4x+0,333...=5x-0,8333...

Solving:

4 x 5 x = 0 , 8333... 0 , 333... 4x-5x=-0,8333...-0,333...

x = 1 , 1666.... -x=-1,1666....

x = 1 , 1666.... x=1,1666....

This value is in hours. In minutes is 70.

The distance formula is V = S T V=\frac { S }{ T }

5 = S 70 10 5=\frac { S }{ 70-10 }

5 = S 60 5=\frac { S }{ 60 }

60 minutes is 1 hour. The velocity is in miles per hour, the time and the distance must be measured in hours and miles respectively.

5 = S 1 5=\frac { S }{ 1}

5 × 1 = S 5\times 1=S

S = 5 S=5

The distance from Paul's house to school is 5 miles.

Compare the 2 given events and find the time taken (t) and put in any of the 2 eqn to get the Distance (d) ....d=5 miles

Kevin Patel - 7 years, 1 month ago
Sajjad Khan
Jun 3, 2014

let time be 'x', as we know D=VxT then for first case(V=5,T=X) D=5X.... for second case (V=4, T= X+1/4 hours) D=4(X+1/4)..... solving simultaneously X=1 then Distance(D)=5miles

Maxis Jaisi
May 29, 2014

Let the distance be d.

When he's on time, he walks with speed x, hence t = d/x.

When he's early, the time t1 is d/5.

When he's late, the time t2 is d/4.

d/x - d/5 = 1/6 ( 10 min difference )

d/4 - d/x = 1/12 ( 5 min difference )

The distance follows. :)

Ryan Redz
May 19, 2014

d/5 = t-1/6 (equation 1) note: 1/6 is 10 minutes converted to hrs. d/4 = t + 1/12 (equation 2) note 1/12 is 5 minutes converted to hrs., then solve for d. so, d=5.

Rishik Jain
May 6, 2014

Let the distance be x x

Time (1)= x 5 \dfrac{x}{5}

Time (2)= x 4 \dfrac{x}{4}

The difference between their time is 10 + 5 = 15 10+ 5= 15 minutes = 1 / 4 = 1/4 hour.

Clearly,

x 5 + 1 4 = x 4 \dfrac{x}{5} + \dfrac{1}{4} = \dfrac{x}{4}

x 20 = 1 4 \dfrac{x}{20} = \dfrac{1}{4}

x = 5 \large\boxed{x=5}

Hence, the distance is 5 miles.

Sujay Sheth
May 4, 2014

d=5(t-10)/60=4(t+5)/60

5t-50=4t+20

t=70

d=5(t-10)/60

d=5(70-10)60

d=5

Kshitij Johary
May 4, 2014

If Paul walks at 5 miles per hour, he reaches 10 minutes early, but if he walks at 4 miles per hour, he reaches 5 minutes late. Therefore, the time difference to cover the same distance is 15 minutes. Now,

t 1 = d s 1 t_{1} = \frac {d}{s_{1}} ,

where t 1 t_{1} is the time taken when walking at s 1 = 5 m i l e s p e r h o u r s_{1} = {5} {miles} {per} {hour} .

Similarly,

t 2 = d s 2 t_{2} = \frac {d}{s_{2}} ,

where t 2 t_{2} is the time taken when walking at s 2 = 4 m i l e s p e r h o u r s_{2} = 4 miles per hour .

We know that,

t 2 t 1 = 15 t_{2} - t_{1} = 15 .

Substituting the values and solving for d, we get

d = 5 m i l e s \boxed {d = 5 miles} .

Hey yo,

For 5mph, 10 minutes earlier, by applying v = s/t ,

5 = s / (t - 10/60)

5 = s / ( t - 1/6)

5( 6t - 1) = 6s

30t - 5 = 6s

30t - 5 = 2(3s) (1st),

For 4mph, 5 minutes late,

4 = s / ( t + 5/60 )

4 = s / ( t + 1/12 )

4(12t + 1) = 12s

12t + 1 = 3s (2nd),

By substituting (2nd) into (1st),

30t - 5 = 2( 12t + 1)

6t = 7

t = 7/6 hours,

therefore,

s = 12(7/6) + 1 / 3 = 15/3 = 5 miles...

thanks...

Sameh Rehan
May 3, 2014

distance = 5/60 (t - 10) = 4/60 (t+5) -> t = 70 mins -> distance = 5 miles.

distance (mile) = velocity (mile / min) * time (min)

Sameh Rehan - 7 years, 1 month ago

Separate everything into rate time and distance

t= on time

5 (t-1/6) = 4 (t+1/12)

t= 7/6

d= 5

Faizan Baig
May 3, 2014

Time for 1st: Distance/Speed = x/5,

Time for 2nd : x/4,

Slower Time is x/4 and faster is x/5,

Equation: slower time - faster time = difference of time,

x/4 - x/5 = 15/60

Take LCM

5x- 4x = 20*3/12

x = 5 miles (distance travelled)

Satyen Nabar
May 2, 2014

Let time taken usually be T.

Distance D =5(T-10/60) = 4(T+5/60)

Solving T = 7/6.

D= 5(7/6-10/60) = 5

But shortcut method add time ie 10+5=15 And multiply speed ie 5 4=20 And as we know D=S T 15/60*20=5 Whc is the answer...:)

Vikramjit Singh Janjua - 7 years, 1 month ago

I dont undrstand the last step. Watz the need to multiply 7/6 with 5 in order to find the distance ?

Disha Mohanty - 7 years, 1 month ago

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