A ship sails north for 2 hours, traveling a total of 15 miles. Then the ship turns south and travels 6 miles in an hour. If north is taken as the positive direction, what is the velocity of the ship?

7 miles per hour ,

3 miles per hour ,

–3 miles per hour ,

–7 miles per hour

3 miles per hour

Explanation:

Displacement is the overall change in distance or position of an object. It is the shortest distance from the starting point to the ending point. Displacement is a vector quantity.

Velocity is the time rate of change in displacement, it is the ratio of the total displacement to the total time taken. It is given by the formula:

Velocity = displacement / time

The ship sails north for 2 hours, traveling a total of 15 miles. Then the ship turns south and travels 6 miles in an hour.

The total displacement = shortest distance from initial to final point = 15 miles - 6 miles = 9 miles

Total time = (2 hours) + (1 hour) = 3 hours

Velocity = displacement / time = 9 miles / 3 hours = 3 miles per hour

the old price per ounce is c/4.

the new price per ounce is c/3.6.

the ratio of the old price to the new one is

(c/4)/(c/3.6) = (c/c)×(3.6/4) = 0.9 . . = 9/10 . . "nine tenths" in either form