Answer:
4400 yards
Step-by-step explanation:
Many folks remember there are 5280 feet in a mile. Then 2.5 miles is ...
(2.5 mi)(5280 ft/mi) = 13,200 ft
There are 3 feet in a yard, so the number of yards in 2.5 miles is ...
(13,200 ft)/(3 ft/yd) = 4,400 yd
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Of course, this is easier if you remember there are 1760 yards in a mile.
(2.5 mi)(1760 yd/mi) = 4,400 yd
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Additional comment
In general, units conversion is accomplished using conversion factors that have a value of 1. That is, they are a fraction whose numerator and denominator are equal, but expressed in different units. The units of the conversion factor are chosen to cancel the units you don't want and leave a result in units you do want.
[tex]2.5\text{ mi}\times\dfrac{5280\text{ ft}}{1\text{ mi}}\times\dfrac{1\text{ yd}}{3\text{ ft}}=\dfrac{2.5\times5280\text{ mi$\cdot$ft$\cdot$yd}}{3\text{ mi$\cdot$ft}}=\dfrac{13200}{3}\text{ yd=\boxed{4400\text{ yd}}}[/tex]
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You might remember there are 1760 yards in a mile, because a typical high-school oblong running track is 440 yards, or 1/4 mile.
