In 1985, the cost of clothing for a certain family was $620

In 1985, the cost of clothing for a certain family was $620. In 1995, 10 years later, the cost of clothing for this family was $1,000. Assuming the cost increased linearly, what was the cost of this family’s clothing in 1991 ?

1. $908
2. $848
3. $812
4. $810
5. $772

Answer

The correct answer is B.

Assuming the cost increased linearly is equivalent to assuming the cost increased at a constant rate. Because the cost of the clothing increased from $620 to $1,000 in 10 years, the constant rate is equal to

= ($1,000 - $620)/10

= $38 per year

Therefore, the cost of the family’s clothing in 1991 (6 years after 1985) is:

$620 + (6 years)($38 per year)

= $620 + $228

= $848