On average, an adult human body contains approximately how many pints of blood?

Introduction / Context:
Knowing the approximate volume of blood in the human body is important for understanding blood loss, transfusions, and circulation. While the exact amount depends on body size, sex, and health, typical textbook questions use a rounded range. This question asks you to select the approximate number of pints of blood in an average adult human.

Given Data / Assumptions:

• The person is an average sized healthy adult.
• We are asked for an approximate volume expressed in pints.
• Common medical estimates suggest 5 to 6 litres of blood in an adult.
• One pint is a little more than half a litre, so 5 to 6 litres can be expressed as a certain range of pints.

Concept / Approach:
Medical references often state that an adult human has about 5 to 6 litres of blood. If we convert this to pints, using a rough conversion of about 0.5 to 0.6 litre per pint, we find that 5 to 6 litres corresponds to approximately 8 to 10 pints of blood. This is why many general knowledge sources and first aid manuals mention that the average adult has about 8 to 10 pints of blood. Therefore, among the ranges given, 8 - 10 pints best matches standard estimates.

Step-by-Step Solution:
Step 1: Recall the typical blood volume of an adult: around 5 to 6 litres. Step 2: Use the rough conversion that 1 pint is slightly over 0.5 litre. Step 3: Estimate the number of pints by dividing 5 to 6 litres by about 0.5 to 0.6 litre per pint. Step 4: This gives a value close to 8 to 10 pints in total. Step 5: Compare this with the option ranges provided and see that 8 - 10 is the best fit. Step 6: Therefore, the approximate number of pints of blood in an average adult is 8 - 10.

Verification / Alternative check:
First aid and physiology guides commonly state that an average adult has about 5 litres of blood and that losing more than 40 percent can be life threatening. They often give equivalent quantities in pints for practical use in transfusion and donation contexts. Blood donation services sometimes mention that an adult has about 8 to 10 pints of blood, which matches the calculation above. This cross checking supports 8 - 10 pints as the appropriate range.

Why Other Options Are Wrong:
6 - 8: This range corresponds to a lower total blood volume than 5 to 6 litres and underestimates typical adult blood volume. 10 - 12: This range is slightly higher than expected and would correspond to a much larger total blood volume than average. 5 - 7 and 3 - 5: These ranges are also too low in pints compared with the known litre volume.

Common Pitfalls:
Students sometimes mix up litres and pints or memorise only one of these units. Another common error is to underestimate blood volume by thinking of just the visual amount seen in injuries. Remember that the circulatory system fills all blood vessels and organs, so the total blood volume is significantly larger than what is usually imagined from a small spill.

Final Answer:
The correct answer is 8 - 10.