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Finding the Fourth Proportional to 781.58, 1,078.58 and 515.70

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Solution

The fourth proportional to 781.58, 1,078.58 and 515.70 is: 711.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    781.58 : 1,078.58 = 515.70 : x
  2. Step 2: Convert to fraction form
    781.58/1,078.58 = 515.70/x
  3. Step 3: Cross multiply
    781.58x = 1,078.58 × 515.70
  4. Step 4: Simplify right side
    781.58x = 556,225.00
  5. Step 5: Solve for x
    x = 556,225.00/781.58
  6. Step 6: Final answer
    x = 711.67

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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.