Download Ratio and Proportion:

Ratio and Proportion:
1 is to 2 as 2 is to 4
1:2 = 2:4
1
: 2 = 2 : 4
Extreme:Mean=Mean:Extreme
Using means and extremes –
Means - the number directly next to each side of the equal signs.
Extremes – the number on the outside on each side of the equal signs.
When finding ration and proportion, once the problem is completed properly, multiplying
the means together should equal multiplying the extremes together.
1:2 = 2:4
Extremes - 1 and 4
Means above – 2 and 2
2 is to 4 as 4 is to 8
2:4 = 4:8
Extremes – 2 x 8 = 16
Means –
4 x 4 = 16
4 is to 8 as 8 is to 16
4:8 = 8:16
Extremes 4 x 16 = 64
Means 8 x 8 = 64
1x4=4
2x2=4
Using x:
1:2 = 2:X
Extremes –
Means -
1 x X = 1X
2x2= 4
To isolate “X” divide whatever is with “X” by itself to get “1”
2X = 1X = X
2
4X = 1X = X
4
100X = 1X = X
100
487X = 1X = X
487
Once you have isolated X, you must divide the other side of the equals side by the same
thing – whatever you do to one side of an equation you must do to the other.
If you have 14:28 = 2:X
14X = 56
14X = 56
14
14
X=4
To check this problem – insert the answer for X into the equation to make sure it is
accurate.
14:28 = 2:4
Means
28 X 2 = 56
Extremes
14 X 4 = 56
Adding labels:
1000 mg: 1Gm = X mg: 4 Gm
1X = 4000 (mg)
50 mg: 1 tab = 150 mg: X tabs (you will always be multiplying opposite labels)
50X = 150
50
50
X = 3 (tabs)
50 mg: 1 tab = 150 mg: 3 tabs
Practice problems:
1)
A patient is to receive Valium 10 mg TID. The available tablets are labeled 5
mg.
How many tabs will you give?
2)
The physician orders Lasix 40 mg. The drug label reads Lasix 20 mg/ml.
What will you give?
3)
The physician orders 5 mg of a drug to be given. You have 2.5 mg tabs
available.
How many tabs should you give?
4)
You have 15 mg/ml of Morphine Sulfate. The order is for 10 mg to be given.
How much should be administered?
5)
The physician orders Gentamycin 60 mg IM. The drug label reads
Gentamycin 40 mg/mL.
How much will you give?
6)
The order is for Librium 25 mg IM. The drug label reads Librium 100 mg/2ml.
How much will you give?
7)
The physician orders Digoxin 0.5 mg. The drug label reads Digoxin 0.25 mg
per tab.
What will you give?
8)
The order is for Pen-Vee K 250 mg. The drug label reads Pen-Vee K
125mg/ml.
How much will you give?
Solutions to Practice problems:
1)
A patient is to receive Valium 10 mg TID. The available tablets are labeled 5 mg.
How many tabs will you give?
5 mg: 1 tab = 10 mg: X tabs
Means
Extremes
1 X 10 = 10
5 X “X” = 5X
5X = 10
5
5
X = 2 (tabs)
2)
The physician orders Lasix 40 mg. The drug label reads Lasix 20 mg/ml.
What will you give?
20 mg: 1 mL = 40 mg: X mL
Means
Extremes
1 X 40 = 40
20 X “X” = 20 X
20X = 40
20
20
X = 2 (mL)
3)
The physician orders 5 mg of a drug to be given. You have 2.5 mg tabs
available.
How many tabs should you give?
2 tabs
4)
You have 15 mg/ml of Morphine Sulfate. The order is for 10 mg to be given.
How much should be administered?
0.67 mL
5)
The physician orders Gentamycin 60 mg IM. The drug label reads Gentamycin 40 mg/mL.
How much will you give?
1.5 mL
6)
The order is for Librium 25 mg IM. The drug label reads Librium 100 mg/2ml.
How much will you give?
0.5 mL
7) The physician orders Digoxin 0.5 mg. The drug label reads Digoxin 0.25 mg per tab.
What will you give?
2 tabs
8) The order is for Pen-Vee K 250 mg. The drug label reads Pen-Vee K 125mg/ml.
How much will you give?
2 mL