Question

After lunch, Hailey goes to the pet store. Suppose Hailey buys 5 guinea pigs at 20% off the original price of g dollars per guinea pig, which expression will NOT give Hailey's total cost?
A) 4g
B) 5g
C) 5g − 0.2(5g)
D) 5g − 1g

Answer 1

Option B

The expression 5g will NOT give Hailey's total cost

Solution:

Given that Hailey buys 5 guinea pigs at 20% off the original price of g dollars per guinea pig

From given information,

Number of guinea pigs bought = 5

Original price = g dollars

Given that Hailey has bought 5 guinea pigs at 20% off

Price at which hailey bought pigs after offer is given as:

price per guinea pig after offer = g - 20 % of g

Total cost for 5 guinea pigs:

Total cost = 5(g - 20% of g)

$\text{ Total cost } = 5g - 5 \times \frac{20}{100} \times g$

The above expression can be written in different ways:

$5g - 5 \times \frac{20}{100} \times g = 5g - 1g$

or

$5g - 5 \times \frac{20}{100} \times g = 5g - 5 \times 0.20g = 5g - 0.2(5g)$

or

$5g - 5 \times \frac{20}{100} \times g = 5g - 1g = 4g$

Thus Option A, Option C, Option D are correct

So Option B will NOT give Hailey's total cost