All categories

2 years ago

7. A train which is 100 meters long is traveling at a speed of 90 km per hour. How many

Mathematics

1 answer:

Naily [24]2 years ago

8 0

Answer:

D; 16 seconds

Step-by-step explanation:

speed = distance/time

speed = 90 km/hr

We need to convert this to m/s because the tunnel is in meters and the time is in seconds:

$\frac{90km}{hr} * \frac{1hr}{3600s} *\frac{1000m}{1km} =25m/s$

distance = 300 m (tunnel) + 100 m (train) = 400 meters

Solving for time:

$25m/s=\frac{400m}{t} \\(25m/s)(t)=400m\\t=\frac{400m}{25m/s} \\t=16 s$

You might be interested in

Please help me thank you.

Alona [7]

Answer:

$\large\boxed{1.\ (4)^{-3x^2}=\left(\dfrac{1}{4}\right)^{3x^2}}$

$\large\boxed{2.\ ab^{-3x}=a\left(\dfrac{1}{b}\right)^{3x}=a\left[\left(\dfrac{1}{b}\right)^3\right]^x}$

Step-by-step explanation:

$Use:\ a^{-n}=\left(\dfrac{1}{a}\right)^n\\------------\\\\(4)^{-3x^2}=\left[(4)^{-1}\right]^{3x^2}=\left(\dfrac{1}{4}\right)^{3x^2}$

$Use:\ a^{-n}=\left(\dfrac{1}{a}\right)^n\ and\ (a^n)^m=a^{nm}\\--------------------\\\\ab^{-3x}=a\cdot b^{-3x}=a\left[(b)^{-1}\right]^{3x}=a\left(\dfrac{1}{b}\right)^{3x}\\\\ab^{-3x}=a\left(\dfrac{1}{b}\right)^{3x}=a\left[\left(\dfrac{1}{b}\right)^3\right]^x$

8 0

2 years ago

What is the amswer to -4k-2(k-3)=-6k+8

SashulF [63]

Answer:

k = 1/2

Step-by-step explanation:

-4k-2(k)-2(-3)=-6k+8

-4k-2k+6=-6k+8

-2k+6=-6k+8

4k+6=8

4k=2

4k/4= 2/4

k=1/2

4 0

3 years ago

14.1-191 Is this the answer?

enyata [817]

I don’t know if this is what you’re asking but 14.1-191 = -176.9

4 0

2 years ago

Read 2 more answers

jackie drove 7 hours at an average of 60 miles an hour...how far did she travel... pls hurry i need to know soon thx

Furkat [3]

Answer: 420 miles

Step-by-step explanation: She drove 7 hours at an average of 60 mph. You have to do 7 times 60 because each hour she goes 60 miles. 7 multiplied by 60 will give you 420.

4 0

3 years ago

3 cans that store 9 tennis balls... Find the constant of proportionality & write a equation to represent the relationship PL

Lilit [14]

3 cans store 9 tennis balls.
Find the Constant of proportionality and write and equation with regards to this given situation:
=> number of tennis balls = 9
=> number of cans = 3

 So the constant of proportionality is in the working column. Pls see attached.

7 0

3 years ago