Sure, let's solve this step by step:

Step 1: Let's denote the four numbers as a, b, c, and d.

Step 2: According to the problem, the average of any three numbers added to the fourth gives either 28, 21, 18, or 25. This means:

(a+b+c)/3 + d = 28,
(a+b+d)/3 + c = 21,
(a+c+d)/3 + b = 18,
(b+c+d)/3 + a = 25.

Step 3: Multiply each equation by 3 to simplify:

a+b+c+3d = 84,
a+b+3c+d = 63,
a+3b+c+d = 54,
3a+b+c+d = 75.

Step 4: Add all four equations together:

6a+6b+6c+6d = 276.

Step 5: Divide the equation by 6:

a+b+c+d = 46.

Step 6: To find the average of the four numbers, divide the sum by 4:

Average = (a+b+c+d)/4 = 46/4 = 11.5.

So, the average of the original four numbers is 11.5.

Question

Sure, let's solve this step by step:

Step 1: Let's denote the four numbers as a, b, c, and d.

Step 2: According to the problem, the average of any three numbers added to the fourth gives either 28, 21, 18, or 25. This means:

(a+b+c)/3 + d = 28,
(a+b+d)/3 + c = 21,
(a+c+d)/3 + b = 18,
(b+c+d)/3 + a = 25.

Step 3: Multiply each equation by 3 to simplify:

a+b+c+3d = 84,
a+b+3c+d = 63,
a+3b+c+d = 54,
3a+b+c+d = 75.

Step 4: Add all four equations together:

6a+6b+6c+6d = 276.

Step 5: Divide the equation by 6:

a+b+c+d = 46.

Step 6: To find the average of the four numbers, divide the sum by 4:

Average = (a+b+c+d)/4 = 46/4 = 11.5.

So, the average of the original four numbers is 11.5.

Knowee AI · Accepted Answer