9514 1404 393
Answer:
1 < 15 -2a < 7
Step-by-step explanation:
There are a couple of ways you can do this.
1) Put the minimum and maximum values of a into the expression to see what its corresponding values are:
15-2a for a=4:
15-2(4) = 7
15-2a for a=7:
15-2(7) = 1
Then ...
1 < 15-2a < 7
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2) Solve for a in terms of the value of 15-2a, then impose the limits on a.
x = 15 -2a
2a = 15 -x
a = (15 -x)/2
Now, impose the given limits:
4 < (15 -x)/2 < 7
8 < 15 -x < 14 . . . multiply by 2
-7 < -x < -1 . . . . . . subtract 15
7 > x > 1 . . . . . . . . multiply by -1
1 < 15-2a < 7 . . . . . use x=15-2a
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The vertical extent of the attached graph is the range of possible values of 15-2a. It goes from 1 to 7.
General Idea:
The volume of cylinder is given by
, where r is the radius and h is the height of the cylinder.
Applying the concept:
Step 1: We need to find the volume of full cylinder with the given dimensions using the formula.
Volume of full cylinder 
Volume of half cylinder 
Step 2: Let x be the number of minutes of filling the sand.
of sand filled every 15 seconds, there are four 15 seconds in a minute.
So volume of sand filled in 1 minute
.
of sand taken out of cylindrical vase every minute.
Net volume of sand filled in 1 minute = Volume of sand filled in the vase in one minute - Volume of sand taken out in 1 minute
Net volume of sand filled in 1 minute
Volume of sand filled in x minutes
.
We need to set up an equation to find the number of minutes need to fill half the volume in cylindrical vase.

Conclusion:
The number of minutes required for the base be half filled with sand is 57
Answer:
She has 16 friends
Step-by-step explanation:
40 minus 8 is 32 so that divided by 2 is 16
Step-by-step explanation:
the similarity of the triangle:
x/18 = 8/12
=> 12x = 18×8
12x = 144
x = 12