Sorry

This answer is incorrect.

You correctly chose to add the two amounts together. However you must remember that when completing a mixed units problem you must keep track of the units. There are two ways of completing this problem.

Method 1

• Convert everything to the same units
.
• Add.
• Convert back to mixed units.

Example

Say you have to add 5 feet 7 inches to 2 feet 6 inches.

5 feet 7 inches converts as

5 feet x 12 inches/foot = 60 inches

60 inches + 7 inches = 67 inches

2 feet 6 inches converts as

2 feet x 12 inches/foot = 24 inches

24 inches + 6 inches = 30 inches

then

67 inches + 30 inches = 97 inches

Convert this back to mixed units

97 inches divided by 12 inches/foot = 8 feet 1 inch.

Method 2

• Start with the smallest unit.
• Add.
• Convert on the fly.

Example

Say you have to add 5 feet 7 inches to 2 feet 6 inches.

Start with the inches.

7 inches + 6 inches = 13 inches

But 13 inches is more than 1 foot.

13 inches divided by 12 inches/foot = 1 foot 1 inch.

Now add the feet

5 feet + 2 feet + 1 foot (from the inches column) = 8 feet

Therefore the answer is 8 feet 1 inch.

Another Try

If you feel that you understand the above example, let's try another problem.

If George placed a 3 feet 9 inches tall model airplane atop a 1 foot 4 inches tall display base, how tall would the airplane and base be together?

• 5 feet 3 inches
• 2 feet 5 inches
• 5 feet 1 inch
• 4 feet 1 inch

Web Related: David.Mazza@grc.nasa.gov
Technology Related: Thomas.J.Benson@grc.nasa.gov
Responsible NASA Official: Theresa M. Scott (Acting)