Answer:
c
Step-by-step explanation:
I just looked up the question
Answer:
21/4 :3/4= 21/4 *4/3= 7/1 *1/1 = 7
7 bookcases
Step-by-step explanation:
There are 720 ways through which 3 numbers can be selected from 10 numbers to open a keypad lock.
Given that there are 10 numbers are 3 numbers are required to open a keypad lock.
Permutations are the number of ways in which objects can be selected without replacements to form subsets.
It is expressed as n=n!/(n-r)!.
Factorial of a number is the product of consecutive numbers less than the number.
Total numbers available=10
Numbers to be selected=3
Number of ways can be found by using permutations.
Number of ways =10
=10!/(10-3)!
=10!/7!
=10*9*8*7!/7!
=10*9*8
=720 ways.
Hence there are 720 ways through which 3 numbers can be selected from 10 numbers.
Learn more about permutations at brainly.com/question/1216161
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Answer:
The 72 feet is measured on the slope, not out from the pole horizontally. I get
top of pole is at
40 + 72 sin17°
downhill point is
72 cos 17°
from point beneath the pole
cable^2 = (40+72 sin17°)^2 + (72 cos 17°)^2