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Finding the Fourth Proportional to 1,139.09, 1,571.97 and 641.78

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Solution

The fourth proportional to 1,139.09, 1,571.97 and 641.78 is: 885.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,139.09 : 1,571.97 = 641.78 : x
  2. Step 2: Convert to fraction form
    1,139.09/1,571.97 = 641.78/x
  3. Step 3: Cross multiply
    1,139.09x = 1,571.97 × 641.78
  4. Step 4: Simplify right side
    1,139.09x = 1,008,851.05
  5. Step 5: Solve for x
    x = 1,008,851.05/1,139.09
  6. Step 6: Final answer
    x = 885.67

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.