Practice problems · Drip rates · 5 worked
IV drip rate practice problems (gtt/min)
A drip rate problem asks how many drops per minute to count when an infusion runs by gravity. Multiply the volume in milliliters by the tubing's drop factor in drops per milliliter, then divide by the time in minutes. Drops are counted whole, so these answers are rounded to the whole number.
The rounding rule on this page
Every answer here is rounded once, at the end, under one stated rule: nearest tenth, half rounds up, except tablets and capsules, rates in milliliters per hour and drip rates in drops per minute, which go to the nearest whole number, half rounds up. Your program's rule may differ, and on an exam it is the one that counts.
Work each problem on paper first, then open its solution. Each one is one of the 20 problems in DoseReady's gtt per min family, with the numbers the app drew for it.
No licensed clinician has reviewed the problem set. Where a problem and its source disagree, trust the source and what your program teaches.
Problem 1 of 5
An infusion of 500 mL of normal saline is to run by gravity over 100 min. The tubing delivers 10 gtt per milliliter. How many drops per minute are counted?
Show the worked solution
Dimensional analysis
500 × 10 × 1 ÷ 1 ÷ 100 = 50
Ratio and proportion
DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.
Formula method
The formula method (D ÷ H × Q) does not fit this problem. The chain above is the working.
- The working comes to
- 50 gtt/min
- The answer under the stated rule
- 50 gtt/min
- Nearest whole number, half rounds up, the stated rule for drip rates in drops per minute.
What each slip gives here
- Decimal point one place out500 gtt/min or 5 gtt/min
- Conversion factor inverted1 gtt/min or 500,000 gtt/min
- Conversion skipped5,000 gtt/min
Problem 2 of 5
A ceftriaxone minibag of 100 mL is to infuse by gravity over 30 min. The tubing delivers 15 gtt per milliliter. How many drops per minute are counted?
Show the worked solution
Dimensional analysis
100 × 15 × 1 ÷ 1 ÷ 30 = 50
Ratio and proportion
DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.
Formula method
The formula method (D ÷ H × Q) does not fit this problem. The chain above is the working.
- The working comes to
- 50 gtt/min
- The answer under the stated rule
- 50 gtt/min
- Nearest whole number, half rounds up, the stated rule for drip rates in drops per minute.
What each slip gives here
- Decimal point one place out500 gtt/min or 5 gtt/min
- Conversion factor inverted45,000 gtt/min
- Conversion skipped3 gtt/min or 1,500 gtt/min
Problem 3 of 5
At the start of the night shift, 750 mL of normal saline remains in the bag and is to finish by gravity over 10 hr. The tubing delivers 20 gtt per milliliter. How many drops per minute are counted?
Show the worked solution
Dimensional analysis
750 × 20 × 1 × 1 ÷ 1 ÷ 10 ÷ 60 = 25
Ratio and proportion
DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.
Formula method
The formula method (D ÷ H × Q) does not fit this problem. The chain above is the working.
- The working comes to
- 25 gtt/min
- The answer under the stated rule
- 25 gtt/min
- Nearest whole number, half rounds up, the stated rule for drip rates in drops per minute.
What each slip gives here
- Decimal point one place out250 gtt/min or 3 gtt/min
- Conversion factor inverted2,500 gtt/min or 90,000 gtt/min
- Conversion skipped1 gtt/min or 1,500 gtt/min
Problem 4 of 5
A home infusion of normal saline runs by gravity because no pump is supplied. The order reads 90 mL/hr, and the tubing delivers 20 gtt per milliliter. How many drops per minute are counted?
Show the worked solution
Dimensional analysis
90 × 20 × 1 ÷ 1 ÷ 60 = 30
Ratio and proportion
DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.
Formula method
The formula method (D ÷ H × Q) does not fit this problem. The chain above is the working.
- The working comes to
- 30 gtt/min
- The answer under the stated rule
- 30 gtt/min
- Nearest whole number, half rounds up, the stated rule for drip rates in drops per minute.
What each slip gives here
- Decimal point one place out300 gtt/min or 3 gtt/min
- Conversion factor inverted108,000 gtt/min
- Conversion skipped2 gtt/min or 1,800 gtt/min
Problem 5 of 5
An order reads to infuse 600 mL of normal saline by gravity over 150 min. The unit stocks tubing in several sizes, and the set in use delivers 20 gtt per milliliter. How many drops per minute are counted?
Show the worked solution
Dimensional analysis
600 × 20 × 1 ÷ 1 ÷ 150 = 80
Ratio and proportion
DoseReady does not yet set this problem out as a textbook proportion, with like units in the same places, so it is not shown here. The chain above is the working.
Formula method
The formula method (D ÷ H × Q) does not fit this problem. The chain above is the working.
- The working comes to
- 80 gtt/min
- The answer under the stated rule
- 80 gtt/min
- Nearest whole number, half rounds up, the stated rule for drip rates in drops per minute.
What each slip gives here
- Decimal point one place out800 gtt/min or 8 gtt/min
- Conversion factor inverted1,800,000 gtt/min
- Conversion skipped4 gtt/min or 12,000 gtt/min
Practice under your own program's rules
In DoseReady you enter your program's passing score, notation and rounding rule once. Every answer is graded under that rounding rule, and each worked solution is written in your notation where the problem allows it.
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Exam practice, never for patient care.
Guides
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