Suppose that y varies directly with x and y = 10 when x = 20. What is y when x = 15?
1 answer:
Answer: y = 7.5
Step-by-step explanation:
Suppose that y varies directly with x
That is, y∝x
Convert y∝x to a full equation by introducing a constant k to the right hand side.
Therefore, y = kx
Given that y = 10 and x = 20
Substitute y and x in the equation above. We have;
10 = k(20)
10 = 20k
20k = 10
k = 10/20
k = 0.5
Since k = 0.5, the equation y = kx becomes y = 0.5x
Now, to find y if x = 15, substitute x in equation y = 0.5x
Therefore, y = 0.5(15)
y = 7.5
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Answer:
The answer is 21 minutes
Step-by-step explanation:
We use the equation Xf = Xo + vt
1) At 1:00 PM, child one leaves the starting point heading north at a constant velocity of 6 mi/hr or .1 [mi/min] (divide by 60 to convert from [mi/hr] to [mi/min])
2) He walks for 15 minutes before kid 2 starts walking. In 15 minutes he is able to cover 1.5 [mi]
3) Now, child 2 starts walking and we know that when the range reaches 3 miles, they won´t be able to communicate. So the sum of the final position of child 1 and child 2 must be 3[mi]
- Child 1 final position =>
- Child 2 final position =>
4) Sum the equations and equate to 3
5) Substitute the values we already know
6) in 15 + 6 minutes they will be 3miles apart
7) In 21 minutes they will still be able to communicate with one another.