# Subtract 4.66×10^−5 − 7.34×10^−7

−2.68×10^2

−4.5866×10^−5

4.5866×10^−5

2.68×10^2

## The correct answer is 4.5866×10^−5

## The U.S. national debt was $2.9617×10^13 in 2021 and $3.98×10^11 in 1971. Find how much the debt increased in the 50-year period.

$2.9219×10^13

$2.9219×10^11

$3.0015×10^13

$1.0183×10^24

## To find the increase in the debt over the 50-year period, we subtract the initial debt from the final debt.

Final debt: $2.9617×10^13

Initial debt: $3.98×10^11

Subtracting the initial debt from the final debt gives us:

(final debt) - (initial debt) = ($2.9617×10^13) - ($3.98×10^11)

To subtract the debt expressed in scientific notation, the exponents must be the same. We can achieve this by converting the initial debt to scientific notation with an exponent of 13. Thus:

($2.9617×10^13) - ($3.98×10^11) = ($2.9617×10^13) - ($0.398×10^13)

Now we can subtract the two debts:

($2.9617×10^13) - ($0.398×10^13) = $2.5637×10^13

So, the debt increased by $2.5637×10^13 over the 50-year period.

## The size of a hydrogen atom is about 1.2×10^−10 m across. The size of an oxygen atom is 0.000000000152 m across. What is the difference between the sizes of these atoms in scientific notation?

A. 3.2 ×10^−10 m

B. 2.72×10^−10 m

C. 3.2×10^−11 m

D. 3.2×10^−9 m

## To find the difference between the sizes of these atoms, we need to subtract the size of the hydrogen atom from the size of the oxygen atom.

Size of hydrogen atom: 1.2×10^−10 m

Size of oxygen atom: 0.000000000152 m

To subtract the sizes expressed in scientific notation, the exponents must be the same. We can achieve this by converting the size of the hydrogen atom to scientific notation with an exponent of -10. Thus:

1.2×10^−10 m

Now we can subtract the sizes:

0.000000000152 m - 1.2×10^−10 m = 0.000000000152 m - 0.00000000012 m

Now we can calculate the difference:

0.000000000032 m

The difference between the sizes of these atoms in scientific notation is 3.2×10^−11 m.

Therefore, the correct answer is C. 3.2×10^−11 m.

## Platelets and red blood cells are components of the blood. A typical platelet and red blood cell have diameters of approximately 2.33×10^−6 m and 0.0000075 m, respectively. Which blood component has a bigger diameter, and approximately by how much?

A. A red blood cell has a bigger diameter than a platelet by 9.83×10^−6 m.

B. A platelet has a bigger diameter than a red blood cell by 5.17×10^−6 m.

C. A platelet has a bigger diameter than a red blood cell by 9.83×10^−6 m.

D. A red blood cell has a bigger diameter than a platelet by 5.17×10^−6 m.

## To compare the diameters of the platelet and red blood cell, we need to subtract the diameter of the platelet from the diameter of the red blood cell.

Diameter of platelet: 2.33×10^−6 m

Diameter of red blood cell: 0.0000075 m

To subtract the diameters expressed in scientific notation, the exponents must be the same. We can achieve this by converting the diameter of the platelet to scientific notation with an exponent of -6. Thus:

Diameter of platelet: 2.33×10^−6 m

Diameter of red blood cell: 7.5×10^-6 m

Now we can subtract the diameters:

Diameter of red blood cell - Diameter of platelet = 7.5×10^-6 m - 2.33×10^−6 m

= 7.5×10^-6 m - (2.33/100) ×10^−6 m

= 7.5×10^-6 m - 0.0233×10^−6 m

= 0.4767×10^-6 m

= 4.767×10^-7 m

So, a red blood cell has a bigger diameter than a platelet by approximately 4.767×10^-7 m.

Therefore, the correct answer is not among the given options.

## Try again

## Apologies for the incorrect response. Let's compare the diameters of the platelet and red blood cell again.

Diameter of platelet: 2.33×10^−6 m

Diameter of red blood cell: 0.0000075 m

To compare the diameters, we can convert the diameter of the platelet to the same units (meters) as the red blood cell:

Diameter of platelet: 2.33×10^−6 m

Diameter of red blood cell: 7.5×10^−6 m

Comparing the diameters, we can see that the red blood cell has a bigger diameter than the platelet.

To find the difference:

Diameter of red blood cell - Diameter of platelet = 7.5×10^−6 m - 2.33×10^−6 m

= 7.5×10^−6 m - 2.33×10^−6 m

= 5.17×10^−6 m

Therefore, a red blood cell has a bigger diameter than a platelet by approximately 5.17×10^−6 m.

The correct answer is B. A platelet has a bigger diameter than a red blood cell by 5.17×10^−6 m.

## China and India are the most populous countries in the world. China’s population is approximately 1.45×10^9, while India’s population is approximately 1,400,000,000. How many more people live in China than in India?

A. 5×10^9

B. 5×10^10

C. 5×10^7

D. 5×10^8