Red blood cells in human body (scientific notation word problem) | Pre-Algebra | Khan Academy

TL;DR

The video explains how to calculate the number of red blood cells in a human body using scientific notation.

Transcript

A human body has 5 liters of blood, 40% of which is red blood cells. Each red blood cell has a volume of approximately 90 times 10 to the negative 15 liters. How many red blood cells are there in a human body? Write your answer in scientific notation, and round to two decimal places. So they tell us the total volume of blood in the human body. We h... Read More

Key Insights

• 🩸 The human body has 5 liters of blood, with 40% being red blood cells.
• ❎ Each red blood cell has a volume of approximately 90 times 10 to the negative 15 liters.
• 😪 To calculate the number of red blood cells, divide the total volume of red blood cells by the volume of each red blood cell.
• 🛝 The answer should be written in scientific notation, rounded to two decimal places.
• ⌛ The calculation involves multiplying 5 liters by 0.4 and then dividing by 90 times 10 to the negative 15 liters.
• ✊ The resulting answer is approximately 2.22 times 10 to the 13th power.
• 🗂️ To convert the fraction 2/9 into scientific notation, it is multiplied and divided by 10 to yield a value greater than or equal to 1 and less than 10.

Questions & Answers

Q: What is the total volume of blood in the human body?

The total volume of blood in the human body is 5 liters.

Q: What fraction of the total volume of blood is made up of red blood cells?

40% of the total volume of blood is made up of red blood cells.

Q: What is the volume of each red blood cell?

Each red blood cell has a volume of approximately 90 times 10 to the negative 15 liters.

Q: How can we calculate the number of red blood cells in the body?

To calculate the number of red blood cells, divide the total volume of red blood cells (40% of 5 liters) by the volume of each red blood cell (90 times 10 to the negative 15 liters).

Summary & Key Takeaways

• The human body has 5 liters of blood, with 40% of it being red blood cells.

• Each red blood cell has a volume of approximately 90 times 10 to the negative 15 liters.

• To calculate the number of red blood cells, divide the total volume of red blood cells by the volume of each red blood cell.