Answer:
It will take the boulder approximately 4.28 seconds to hit the road
Step-by-step explanation:
The given height of the cliff from which the boulder falls, h = 90 feet
The equation that can be used to find the time it takes the boulder to fall is h = u·t + (1/2)·g·t²
Where;
h = The height of the cliff = 90 ft.
u = The initial velocity of the boulder = 0 m/s (The boulder is assumed to be at rest when it falls)
g - The acceleration due to gravity ≈ 9.81 m/s²
t = How long it will take for the boulder to hit the road below
Plugging in the values gives;
90 = 0 × t + (1/2)×9.81×t² = 4.905·t²
∴ t = √(90/4.905) ≈ 4.28
The time it takes the boulder to hit the road, t ≈ 4.28 seconds.
Ok, so based on a survey - you know that out of 30 students, 11 said that their favourite subject is mathematics. :-)
This means that:
11/30 of these students think mathematics if their favourite subject.
Now, in order to answer your question, we are going to have to change the denominator of the fraction above to 1000. Whatever we do to the denominator of this fraction, we must do to the numerator of this fraction.
Example:
This means that rounded to the nearest ten, theoretically speaking, 370 students out of 1000 would say that mathematics is their favourite subject.
2.25 as a fraction is 2 1/4