Answer
Find the volume of the coin is cubic millimeters.
To prove
Formula
Where r is the radius and h is the height .
As given
The $1 coin depicts Sacagawea and her infant son.
The diameter of the coin is 26.5 mm, and the thickness is 2.00 mm.
Radius = 13.25 mm
Put in the formula
Volume of coin = 3.14 × 13.25 × 13.25 × 2.00
= 1102.53 mm³ (approx)
Therefore the volume of the coin is 1102.53 mm³ .
Notice that
13 - 9 = 4
17 - 13 = 4
so it's likely that each pair of consecutive terms in the sum differ by 4. This means the last term, 149, is equal to 9 plus some multiple of 4 :
149 = 9 + 4k
140 = 4k
k = 140/4
k = 35
This tells you there are 35 + 1 = 36 terms in the sum (since the first term is 9 plus 0 times 4, and the last term is 9 plus 35 times 4). Among the given options, only the first choice contains the same amount of terms.
Put another way, we have
but if we make the sum start at k = 1, we need to replace every instance of k with k - 1, and accordingly adjust the upper limit in the sum.