The CPI and Beyond Math

Question

If it cost $6 to fill a gas tank in 1970, how much would it have cost to fill the same tank in 2010? Thank you so much for the help.

1960: Price = $0.31

Price as a percentage of 1970 price = 86.1%

Price index (1970 = 100) = 86.1

1970: Price = $0.36

Price as a percentage of 1970 price = 100.0%

Price index (1970 = 100) = 100.0

1980: Price = $1.22

Price as a percentage of 1970 price = 338.9%

Price index (1970 = 100) = 338.9

1990: Price = $1.23

Price as a percentage of 1970 price = 341.7%

Price index (1970 = 100) = 341.7

2000: Price = $1.56

Price as a percentage of 1970 price = 433.3%

Price index (1970 = 100) = 433.3

2010: Price = $2.84

Price as a percentage of 1970 price =788.9%

Price index (1970 = 100) = 788.9

Answer 1

2.84/.36 = x/6, if gas prices rose in same percentage as the goods in the CPI

284/6 =x

x= $47.33 for one tank in 2010 if $6 in 1970

7.889x6=$47.33

7.889x.36 = $2.84