Multiply in Scientific Notation Practice

Question

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Question
The average newborn weighs 7.5 pounds. About 4.1×106
babies are born in the United States every year. What is the approximate total weight in pounds of all the babies born in the U.S. in a year? Write the answer in scientific notation, expressed to the exact decimal place.

Answer 1

To find the total weight of all the babies born in the U.S. in a year, you can multiply the average weight of a newborn by the total number of babies born.

Given:

• Average weight of a newborn = \( 7.5 \) pounds
• Number of babies born = \( 4.1 \times 10^6 \)

Now, perform the multiplication:

\[ \text{Total weight} = 7.5 \times (4.1 \times 10^6) \]

First, calculate \( 7.5 \times 4.1 \):

\[ 7.5 \times 4.1 = 30.75 \]

Next, multiply by \( 10^6 \):

\[ 30.75 \times 10^6 \]

Now, we should write \( 30.75 \) in scientific notation. To do that, we express \( 30.75 \) as \( 3.075 \times 10^1 \).

Now combine this with \( 10^6 \):

\[ 3.075 \times 10^1 \times 10^6 = 3.075 \times 10^{1 + 6} = 3.075 \times 10^7 \]

Therefore, the approximate total weight in pounds of all the babies born in the U.S. in a year is:

\[ \boxed{3.075 \times 10^7} \text{ pounds} \]