Question

Every day, 20% of the fish in a fish store are sold. There are 2000 fish left in the store at the end of the day on Tuesday. How many were there when the store opened on Monday, the day before?

Answer 1

If there were 2000 fish left at the end of Tuesday, it means that 80% of the fish were sold. To find the original number of fish, we can use the equation:

80% = 2000 fish
100% = (2000 fish) / (80%)
100% = 2500 fish

So, there were 2500 fish in the store when it opened on Monday.

Answer 2

To determine the number of fish in the store on Monday, we calculate the inverse of two consecutive days of 20% sales from the remaining 2000 fish on Tuesday, resulting in an original count of 3125 fish on Monday.

Step-by-step explanation:

The student is asking how many fish were in the store when it opened on Monday, given that 20% are sold each day and there are 2000 left at the end of Tuesday. To solve this, we need to work backwards from Tuesday's number to determine Monday's starting amount.

Let's define x as the number of fish in the store on Monday morning. After 20% are sold on Monday, 80% of the fish remain. So, we have:

0.8x = number of fish after Monday

Since another 20% are sold on Tuesday, we again have 80% of the remaining fish at the end of Tuesday, which we know to be 2000:

0.8(0.8x) = 2000

This simplifies to:

0.64x = 2000

So:

x = 2000 / 0.64

x = 3125

Therefore, there were 3125 fish in the store when it opened on Monday.