Dana can type 90 words per minute.
Since, 1 minute = hours
Therefore, number of words she can type =
= 90×60
= 5400 words per hour
If she types words in 'x' hours.
Number of words Dana types with the given speed in 'x' hours = Speed of typing × Time
=
Therefore,
hours
Therefore, Dana types words in 48.15 hours.
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The equation that is used to model the length of ladder in terms of x is:
We can model this problem with the help of a right angled triangle whose hypotenuse is 13 meters and the other two legs are x meters and (x-7) meters.
where x is the distance between the top of the ladder and the ground.
and (x-7) is the distance between the foot of the ladder and the wall.
Hence, using Pythagorean Theorem we have:
Hence, the answer is: