Answer:
30 ft
Step-by-step explanation:
We can use the given information to set up a ratio...
![\frac{Mark's\ height}{Mark's\ shadow}=\frac{Tree's\ height}{Tree's\ shadow}](https://tex.z-dn.net/?f=%5Cfrac%7BMark%27s%5C%20height%7D%7BMark%27s%5C%20shadow%7D%3D%5Cfrac%7BTree%27s%5C%20height%7D%7BTree%27s%5C%20shadow%7D)
![\frac{6\ ft}{4\ ft}=\frac{x}{20\ ft}](https://tex.z-dn.net/?f=%5Cfrac%7B6%5C%20ft%7D%7B4%5C%20ft%7D%3D%5Cfrac%7Bx%7D%7B20%5C%20ft%7D)
We can solve this ratio using cross multiplication (multiply the numerator of the first fraction by the denominator of the second and the numerator of the second fraction by the denominator of the first):
120 = 4x
Divide both sides by 4
x=30 ft
Answer:
0.14, 0.5, 0.71, 0.8, 0.83
Let's first break it down to the time 8 people need for one wall. That would be 10 minutes, right? If one person would have to do it in stead of 8, you'd expect him to take 80 minutes.
To paint 7 walls, he would nee 7x80 = 560 minutes. 10 people would do that 10 times faster, ie., 56 minutes.
I know puzzles like these always have a mindtrick. Did I miss anything?? ;-)
Hi there --
If a plane can climb 2,400 feet per minute, it will need 25 minutes to reach 60,000 feet. // By dividing 60,000 (the needed feet) by 2,400 (the amount of feet the plane can climb per/min) you get 25 (the amount of mins needed to climb 60,000 feet)
Hope this helps! Have a great day! :)