Ray and Sam each brought some money for shopping. The ratio of the amount of Ray’s money to the amount of Sam’s money was 3 : 4. After each of them bought a laptop for $1250, the ratio of the amount of Ray’s money to the amount of Sam’s money became 1 : 3. How much money did Sam bring for shopping?

Let the initial amount of money Ray brought for shopping be 3x.

The initial amount of money Sam brought for shopping is 4x.
After buying a laptop, Ray is left with 3x - 1250
After buying a laptop, Sam is left with 4x - 1250
The ratio of the amount of Ray’s money to the amount of Sam’s money became 1 : 3 is 1/3
3x - 1250 = 1/3(4x - 1250)
3(4x - 1250) = (4x - 1250)
12x - 3750 = 4x - 1250
12x - 4x = 3750 - 1250
8x = 2500
x = 2500/8
x = <<2500/8=312.5>>312.5
Sam brought for shopping 312.5 * 4 = <<312.5*4=1250>>1250. Answer: \boxed{1250}.

Let the initial amount of money Ray brought for shopping be 3x.

The initial amount of money Sam brought for shopping is 4x.
After buying a laptop, Ray is left with 3x - 1250
After buying a laptop, Sam is left with 4x - 1250
The ratio of the amount of Ray’s money to the amount of Sam’s money became 1 : 3 is 1/3
3x - 1250 = 1/3(4x - 1250)
x = 500
Sam brought for shopping 500 * 4 = <<500*4=2000>>2000. Answer: \boxed{2000}.

Sorry about that. Let's recheck the solution.

After buying a laptop, Ray is left with 3x - 1250
After buying a laptop, Sam is left with 4x - 1250

The ratio of the amount of Ray’s money to the amount of Sam’s money became 1:3 is 1/3

So, (3x - 1250)/(4x - 1250) = 1/3

Cross multiplying, we have 3(3x - 1250) = 1(4x - 1250)

Simplifying, we get 9x - 3750 = 4x - 1250

Bringing like terms to one side, we have 9x - 4x = 3750 - 1250

5x = 2500

Dividing both sides by 5, we get x = 500

Therefore, Sam brought for shopping 4x = 4(500) = 2000

So, Sam brought 2000 for shopping.

Let's assume that Ray had 3x dollars and Sam had 4x dollars initially.

After buying a laptop for $1250, Ray would have 3x - 1250 dollars and Sam would have 4x - 1250 dollars.

According to the given information, the new ratio of Ray's money to Sam's money is 1:3, so we have the equation:

(3x - 1250) / (4x - 1250) = 1/3

To solve for x, we can cross multiply:

3(4x - 1250) = (3x - 1250)(1)

Simplifying this equation:

12x - 3750 = 3x - 1250

Subtracting 3x from both sides:

9x - 3750 = -1250

Adding 3750 to both sides:

9x = 2500

Dividing both sides by 9:

x = 2500/9 ≈ 277.78

So, Sam originally had 4x dollars, which is 4 * 277.78 ≈ $1111.11.

Therefore, Sam originally brought approximately $1111.11 for shopping.

To solve this problem, let's work step by step.

First, let's represent the amount of money Ray and Sam brought initially.

Let R represent Ray's initial amount of money, and S represent Sam's initial amount of money.

According to the problem, the ratio of Ray's money to Sam's money initially was 3:4. So we can write the equation:

R/S = 3/4

Now, we know that both Ray and Sam bought a laptop for $1250 each. So we subtract $1250 from both their initial amounts of money:

Ray's money after buying the laptop = R - $1250

Sam's money after buying the laptop = S - $1250

According to the problem, after buying the laptops, the new ratio of Ray's money to Sam's money became 1:3. So we can write the equation:

(R - $1250) / (S - $1250) = 1/3

Now we have two equations with two variables. We can solve this system of equations to find the values of R and S.

First, let's simplify the equations by multiplying both sides by the denominators:

For the first equation, multiply both sides by 4:

4 * (R/S) = 4 * (3/4)
4R/S = 3

For the second equation, multiply both sides by 3:

3 * ((R - $1250) / (S - $1250)) = 3 * (1/3)
(R - $1250) / (S - $1250) = 1

Now we have two simplified equations:

4R/S = 3
(R - $1250) / (S - $1250) = 1

Let's solve the second equation. Cross-multiply to eliminate the fraction:

R - $1250 = S - $1250

The "$1250" terms cancel out, leaving us with:

R = S

Now we can substitute this value of R into the first equation:

4R/S = 3
4(S)/S = 3 (substituting R = S)
4 = 3

This is not possible, as 4 cannot be equal to 3.

Therefore, there is no solution to this problem. It seems there may be an error in the given information or problem statement.