A boat, which moves at 12 miles per hour in water without a current, goes 45 miles upstream and 45 miles back again in 8 hours. Find the speed of the current to the nearest tenth.
The speed of the current is
miles per hour.

Given:

Speed in still water = 12 miles per hour

Distance travel in upstream = 45 miles

Distance travel in downstream = 45 miles

Total time = 8 hours

To find:

The speed of current.

Solution:

Let the speed of current be x miles per hour.

Speed in upstream = (12-x) miles per hour

Speed in downstream = (12+x) miles per hour

We know that,

Time to cover 45 miles in upstream =

Time to cover 45 miles in downstream =

Total time is 8 hours. So,

Taking LCM, we get

On further simplification, we get

Taking square root on both sides.

Speed cannot be negative. So, x=3 only.

Therefore, the speed of the current is 3 miles per hour.

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step-by-step explanation:

b: |12 – x| ≤ 0.25

step-by-step explanation:      

let x be the possible lengths in inches, of the ribbons jaime cut.

we have been given that jaime is cutting strips of ribbon for a project. he tries to cut each piece to be 12 inches long, but sometimes he cuts it too long or too short by as much as 0.25 inch.  

we can represent this information in an inequality as:

by the definition of absolute value function we will get,

upon combining our inequalities we will get,

therefore, the inequality   describes all the possible lengths (x), in inches, of the ribbons jaime cut.

step-by-step explanation: