A commuter train travels 45 miles in 28 minutes. what is its speed in miles per hour?

Step-by-step explanation:

-First, you have to find how many miles per minute the train goes.

You do this by dividing 45 by 28.

you get 45/28 miles per minute

-Then, you multiply 45/28 miles per minute by 60.

45 times 60 is 2700.

2700 divided by 28 is 675/7 which is:

Mixed number form: 96 and 3/7 miles per hour

rounded to the tenth: 96.4 miles per hour

rounded to the hundredth: 96.43 miles per hour

rounded to the thousandths: 96.429 miles per hour

96.43 mph to the nearest hundredth.

Step-by-step explanation:

Speed in miles per minute = 45/28

To convert to mph we multiply by 60.

= (45*60)/28

= 96.429

  1.24 weeks

Step-by-step explanation:

The ant population a(t) can be modeled by ...

  a(t) = 400·(700/400)^t . . . . . where t is in weeks

The population will have doubled when a(t) = 800, so we want to find t for ...

  800 = 400·(7/4)^t

  2 = (7/4)^t . . . . . . . . . . . divide by 400

  log(2) = t·log(7/4) . . . . . take the log

  t = log(2)/log(7/4)  ≈ 1.2386 ≈ 1.24 . . . . . weeks

It took about 1.24 weeks for the population to double.