Question

the day before Valentine's Day a store has 400 red roses and 200 boxes of chocolate. After the store opens at 9 a.m. half of the available roses are bought every 2 hours. 15% of the boxes are bought every hour. a. Find a formula that represents the number of red roses left t hours before the store opens. b. Find a formula that represents the number of box chocolates left t hours after the store opens. c. At what time will the number of roses be equal to the number of boxes of chocolates. d. How many boxes of chocolate are left at 12:30 in the afternoon? Round your answer to make sense in this context of the problem. e. Suppose you want to buy that special someone 36 red roses at the store. What is the latest you can arrive to successfully make your purchase?​

Answer 1

Explanation:

a. The number of red roses left t hours before the store opens can be represented by the formula:

N(t) = 400 * (1/2)^(t/2)

Here, we're dividing the number of available roses by 2 every 2 hours, so the exponent t/2 represents the number of 2-hour intervals that have passed since the store opened.

b. The number of box chocolates left t hours after the store opens can be represented by the formula:

M(t) = 200 * (0.85)^t

Here, we're multiplying the number of available boxes by 0.85 every hour, so the exponent t represents the number of hours that have passed since the store opened.

c. We need to find the time t when the number of roses is equal to the number of boxes of chocolates:

400 * (1/2)^(t/2) = 200 * (0.85)^t

Dividing both sides by 200:

2 * (1/2)^(t/2) = 0.85^t

Taking the logarithm of both sides:

log(2) - (t/2) * log(2) = t * log(0.85)

Simplifying:

t * (log(0.85) + (log(2)/2)) = log(2)

t = log(2) / (log(0.85) + (log(2)/2))

Using a calculator, we get:

t ≈ 11.9 hours

Therefore, the number of roses will be equal to the number of boxes of chocolates approximately 11.9 hours before the store opens, or around 9 p.m. on the day before Valentine's Day.

d. To find the number of boxes of chocolate left at 12:30 p.m. (3.5 hours after the store opens), we can use the formula:

M(3.5) = 200 * (0.85)^3.5

M(3.5) ≈ 97.4

Therefore, there are approximately 97 boxes of chocolate left at 12:30 p.m.

e. To buy 36 red roses, we need to find the latest time we can arrive before the store runs out of roses. We can set N(t) equal to 36 and solve for t:

400 * (1/2)^(t/2) = 36

Dividing both sides by 400:

(1/2)^(t/2) = 0.09

Taking the logarithm of both sides:

t/2 * log(1/2) = log(0.09)

Simplifying:

t ≈ 5.2 hours

Therefore, the latest time we can arrive to successfully buy 36 red roses is approximately 5.2 hours before the store opens, or around 3:50 a.m. on the day before Valentine's Day.