Calculation Sample Questions
How much Lidocaine is required to prepare 1 : 1000, 30 cc of solution of Lidocaine?
a. 10 mg
b. 0.03 mg
c. 30 mg
d. 300 mg
View Answer
1. (c) 1: 1000 generally interprets as 1 gm in 1000cc solution. The amount of lidocaine in 30cc of 1:1000 solution can be calculated as follows:
= 30 x 1/1000 = 0.03 gm = 30 milligrams.
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2. How many cc of 75 % alcohol should mix with 10 % of 1000cc alcohol to prepare 30% of 500cc alcohol solution?
a. 346.16 cc
b. 234.43 cc
c. 153.84 cc
d. 121.12 cc
View Answer
2. (c) To solve this type of problem, we need to use alligation method.
75 20 (75%)
30
10 45 (10%)
Total parts 65 (30%)
To prepare 65 (30%) 20 parts (75%) need
To prepare 500 (30%) ?
= 500 x 20/65 = 153.84cc (75%) alcohol
If we mixed 153.84 cc of 75% alcohol with 346.16cc [500cc - 153.84] of 10% alcohol, then we can get 500cc of 30% alcohol solution.
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3. If 60 gm of 1% hydrocortisone is mixed with 80 gm of 2.5% of hydrocortisone, what is the % of hydrocortisone in final mixture?
a. 2.2 % w/w
b. 1.85 % w/w
c. 0.25 % w/w
d. 1.75 % w/w
View Answer
3.(b) Amount of Hydrocortisone in 60 gm, 1%
= 60/100 = 0.6 gm of hydrocortisone.
Amount of hydrocortisone in 80 gm, 2.5%
= 80 x 2.5/100 = 2 gm hydrocortisone
% amount of hydrocortisone in final mixture
= 100 x 2.6 (2gm + 0.6gm)/140 (80gm + 60gm)
= 1.85% w/w.
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4. If 1000 tablets of Risperdal 1 mg cost $ 2250 and % mark up on prescription is 20, what would be the retail price of 30 tablets?
a. $ 150
b. $ 17
c. $ 500
d. $ 81
View Answer
4. (d) 1000 tablets of Risperdal 1mg cost $ 2250. The % mark up on prescription is 20%.
Therefore retail price of 1000 tablets would be:
= 120 x 2250/100 = $ 2700 ** For each $ 100 cost = $120 retail cost**
Price for 30 tablet would be:
= 30 x 2700/1000 = $ 81
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5. If the ratio of ionized to unionized species of drug is 103 and PKa = 2.2, what is the PH of the solution?
a. 2.2
b. 0.8
c. 5.2
d. 3.0
View Answer
5. (c) A pH of the solution can be found by the following formula:
pH = pKa + log ionize/unionize
= 2.2 + log 103
= 2.2 + 3
= 5.2
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6. If dropper is calibrated to deliver 325 mg of iron sulfate in 0.6 cc and adult dose of drug is 325 mg , what is the dose of a drug in cc for a 15 months-old infant?
a. 1.2 cc
b. 0.3 cc
c. 0.06 cc
d. 0.01 cc
View Answer
6. (c) 0.06cc. According to Fried’s rule:
= age in months/150 x adult dose
= 15 x 325/150 = 32.5 mg
The dropper is calibrated to deliver 325 mg of Iron sulfate in 0.6 cc, therefore:
= 0.6 x 32.5/325 = 0.06cc
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7. If the dose of a drug is 10 mg/kg/day, how many 250 mg/100cc ready infusion-bags require to fill above order? Patient's weight is 156 lbs.
a. 1 bag
b. 2 bags
c. 3 bags
d. 5 bags
View Answer
7. (c) Patient weight is 156 lbs, therefore weight in Kg would be 156/2.2 = 70.9 kg
A normal therapeutically recommended dose of drug is 10mg/kg/day, therefore dose in above patient
= 10 x 70.9
= 709 mg
Each ready-infusion-bag contains 250 mg of drug, so number of bags require to fill order would be:
= 709/250 = 2.83 = 3 bags.
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8.How much of atropine is required to prepare 240cc in such way that when 1 teaspoonful of the solution is diluted to 1 pint gives 1 in 500 solution?
a. 2.25 gm
b. 46.08 gm
c. 35.15 gm
d. 25.35 gm
View Answer
8. (b) To solve this kind of problem, we must first find out the amount of drug present in final solution.
Amount of atropine in 1 pint, 1 in 500 soln.
= 480 x 1 /500= 0.96 gm of atropine.
Now, 0.96 gm of drug must be present in 1 teaspoonful of drug solution, therefore we can say:
5cc (1 teaspoonful) contains 0.96 gm
240cc solution requires ?
= 240 x 0.96/5 = 46.08 gm of atropine.
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9. How much sodium bicarbonate powder is required to prepare 240cc of 0.10 N solution of sodium bicarbonate? a. 1.35 gm
b. 3.25 gm
c. 4.81 gm
d. 2.016 gm
View Answer
9. (d) Gram equivalent weights of solute in 1 liter of solution is defined as normality, therefore 1N solution of sodium bicarbonate will contain 84 gms in 1000 cc. We want to find quantity of sodium bicarbonate in 240cc, 0.1 N solution:
1 N solution contains 84 gm
0.1 N solution contains ?
= 0.1 x 84 = 8.4 gms/1000cc.
240cc solution will contain:
= 240 x 8.4/1000 = 2.016 gm of NaHCO3
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10. How many meq of Na+ are present in 0.9% 250cc normal saline solution? [Na+ = 23, Cl- = 35.5]
a. 23.12 meq
b. 15.17 meq
c. 53.15 meq
d. 38.46 meq
View Answer
10. (d) An amount of sodium chloride presents in 250 cc of 0.9% NaCl,
= 250 x 0.9/100 = 2.25 gm NaCl
Total equivalents Na+ = weight in gm
equivalent wt
= 2.25/58.5 = 0.03846 equivalents
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11. If the probability of success in Null hypothesis is 0.6, what is the probability of failure?
a. 0.3
b. 0.9
c. 0.6
d. 0.4
View Answer
11. (d) The sum of probability of success and failure would be equal to 1 in Null hypothesis and can be expressed by following formula:
p + q = 1, where p = probability of success
q = probability of failure
q = 1 - p
= 1- 0.6
= 0.4
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12. How many grams of cocabutter are required to dispense 12 suppositories of tannic acid each weighing 2 gm and contain 400 mg of tannic acid?
a. 21.23 gm
b. 18.67 gm
c. 14.12 gm
d. 13.25 gm
View Answer
12. (b) We want to dispense 12 suppositories each weighing 2gm and containing 400mg of tannic acic:
Amount of coca butter = 2 gm x 12
= 24 gm
Amount of tannic acid = 0.4 gm x 12
= 4.8 gm.
Displacement value of tannic acid is 0.9, therefore:
= 4.8/0.9 = 5.33 gm of base will displace
4.8 gm tannic acid = 5.33 gm cocabutter
Amount of coca butter = 24 gm - 5.33 gm
= 18.67 gm
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13. What is the "mode" or "median" of the following values?
120, 135, 140, 118, 175, 105, 115, 190
a. 135
b. 118
c. 127.5
d. 175
View Answer
13. (c) Median or Mode is generally expressed as a middle value of experiment, if number of values are even, then average of middle values should be considered. To find median or mode of experiment data, one should first arrange the data in ascending or descending order.
In our example,
105, 115, 118, 120, 135, 140, 175, 190
= (120 + 135)/2 = 127.50
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14. If the concentration of reactant M is half in a reaction that is third order in M, by what factor will rate of reaction change?
a. 1/8 times
b. 1/4 times
c. 8 times
d. 4 times
View Answer
14. (a) The concentration of reactant M is half in a reaction that is third order in kinetic:
dx/dt = k (a-x) (b-x) (c-x)
= k (a-x)3 where a=b=c
= k (M)3
now M = M/2
= k (M/2)3
= 1 /8 k (M)3
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15. What is the rate of constant after 90 minutes if the initial concentration of drug is 500mg/cc and 50mg/cc after 90 minutes? (First Order Kinetic)
a. 0.051 min-1
b. 0.025 min-1
c. 0.35 min-1
d. 0.86 min-1
View Answer
15. (b) 0.025 min-1
For the first order kinetic,
K = 2.303/t x log Co/C
= 2.303/90 x log 500/50
= 2.303/90 x log 10
= 0.025 min-1
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16. If the total body clearance of the patient is 2100cc/hr and hepatic clearance is 300cc /hr, what is the status of renal function in a patient?
a. Excellent
b. Normal
c. Moderately impaired
d. Severely impaired
View Answer
16. (d) The status of renal function impairment can be expressed by creatinine clearance.
ClT = ClH + ClR
where,
ClT = Total body clearance
ClH = Hepatic clearance
ClR = Renal clearance
2100 = 300 + ClR
ClR = 1800 ml/hr
= 30 ml/min
The normal creatinine clearance generally lies between 80 to 120 ml/min. A creatinine clearance in patient is 30 ml/min which will be considered severely impaired.
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17. How many grams of sodium chloride are required to prepare 250cc of 1% boric acid solution to isotonic with eye tears?
a. 250 mg
b. 325 mg
c. 991 mg
d. 1221 mg
View Answer
17. (c) Blood serum freezes at 0.520 C, and all solutions having this freezing point are isotonic with blood serum. 0.9% sodium chloride have the same freezing point that of blood serum.
FP provides by 1% Boric acid = -0.29o C
FP of blood = - 0.52o C
FP (needed) by NaCl = (0.52-0.29)
= 0.23o C
Now as we know that FP provides by 1% NaCl would be -0.58o C therefore one can say,
For FP 0.58o needs 1 % NaCl
For FP 0.23o needs ?
= (0.23 x 1)/0.58 = 0.396 % NaCl
0.396 gm of NaCl/ 100cc.
The amount of NaCl needed for 250cc,
= (250 x 0.396)/100 = 0.991 gm NaCl = 991 mg
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