Question

Please help! (25pt and brainliest) From 1970 to 1990, the consumer price index (CPI) increased from 38.8 to 130.7. If a jar of grape jelly cost $0.25 in 1970 and the price of grape jelly increased at the same rate as the CPI from 1970 to 1990, approximately how much did a jar of grape jelly cost in 1990? A. $0.59 B. $0.84 C. $1.31 D. $0.39

Answer 1

Answer:

Option B. $0.84

Step-by-step explanation:

As we know the formula of Consumer Price Index.

$C.P.I.=\frac{P_{1}}{P}\times 100$

Here $p_{1}$ is Current price of the the product.

P = Price of the product in the base year

Now we will plug in the values for year 1970

$38.8=\frac{0.25}{p}\times 100$ ------------(1)

Similarly for the year 1990.

$130.7=\frac{p_{1} }{p}\times 100$  ---------(2)

Now we will divide equation 2 from 1.

$\frac{130.7}{38.8}=\frac{p_{1}}{0.25}$

$P_{1}=\frac{(130.7)(0.25)}{38.8}=0.84$

Therefore, The price of a jar of grape jelly would be $0.84 in 1990.

Answer 2

Formula: cp1/cp2 = price1/price2
so let x be the new price, 
38.8/130.7 = .25/x
x = .25*130.7/38.8
so, you get
x = 0.84