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Finding the Fourth Proportional to 1,399.63, 1,931.49 and 778.63

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Solution

The fourth proportional to 1,399.63, 1,931.49 and 778.63 is: 1,074.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,399.63 : 1,931.49 = 778.63 : x
  2. Step 2: Convert to fraction form
    1,399.63/1,931.49 = 778.63/x
  3. Step 3: Cross multiply
    1,399.63x = 1,931.49 × 778.63
  4. Step 4: Simplify right side
    1,399.63x = 1,503,906.40
  5. Step 5: Solve for x
    x = 1,503,906.40/1,399.63
  6. Step 6: Final answer
    x = 1,074.51

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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.