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Marat540 [252]
3 years ago
15

M is directly proportional to r2.when r=2,m=14.Work out the value of r when m =224

Mathematics
1 answer:
DENIUS [597]3 years ago
6 0

Answer:

r=8

Step-by-step explanation:

we know that

A relationship between two variables, x, and y, represent a proportional variation if it can be expressed in the form  y=kx

In this problem

Let

y=m

x=r^{2}

substitute

m=kr^{2}

<u>Find the value of k</u>

For r=2, m=14

14=k(2^{2})

14=4k

k=14/4 ----> constant of proportionality

the equation is equal to

m=(14/4)r^{2}

Find the value of r when m=224

substitute in the equation and solve for r

224=(14/4)r^{2}

r^{2}=224*4/14

r^{2}=64

r=8

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Yakvenalex [24]

Answers:


a) w+c = 5 ____equation(1) and w = c ____equation (2)


b) 2.5 lb walnuts and 2.5 lb cashews


Step-by-step explanation:


Let w pounds be the weight of walnuts required and c pounds be the weight of cashews required to make the new mixture.


Total weight of the new mixture = 5 lb


So,


Weight of walnuts + Weight of cashews = Total weight of the new mixture


w+c = 5 ____equation (1)


Now,


60% of walnuts +40% of cashews = 20% of walnuts + 80% of cashews


0.60w+0.40c = 0.20w+0.80c


Subtracting 0.20w from both the sides of the equation, we get


0.60w+0.40c-0.20w = 0.20w+0.80c-0.20w


Cancelling out the 0.20w and -0.20w from the right side, we have


0.60w-0.20w+0.40c = 0.80c


=> 0.40w+0.40c=0.80c


Subtracting 0.40c from both sides, we get


0.40w+0.40c-0.40c=0.80c-0.40c


Cancelling out 0.40c and -0.40 c form the left side, we get


0.40w = 0.40c


Dividing both sides by 0.40, we have


\frac{0.40w}{0.40} = \frac{0.40c}{0.40}


Cancelling out the 0.40's from the top and bottom, we get


w = c ____equation (2)


Plugging in w=c into the equation 1, we get


w+c = 5


=> c+c =5


=> 2c = 5


Dividing both sides by 2, we get


\frac{2c}{2} = \frac{5}{2}


Cancelling out the 2's from the left, we get


c = 2.5


Plugging in c=2.5 into the equation 1, we get


w+c = 5


=> w + 2.5 = 5


Subtracting 2.5 from both sides, we get


w+ 2.5 -2.5 = 5 - 2.5


Cancelling out the +2.5 and -2.5 from the left side, we get


w = 2.5


So, we need 2.5 lb walnuts and 2.5 lb cashews to make the new mixture.


- R3KTFORGOOD ☕


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