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Finding the Fourth Proportional to 876.20, 1,209.89 and 782.78

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Solution

The fourth proportional to 876.20, 1,209.89 and 782.78 is: 1,080.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    876.20 : 1,209.89 = 782.78 : x
  2. Step 2: Convert to fraction form
    876.20/1,209.89 = 782.78/x
  3. Step 3: Cross multiply
    876.20x = 1,209.89 × 782.78
  4. Step 4: Simplify right side
    876.20x = 947,077.69
  5. Step 5: Solve for x
    x = 947,077.69/876.20
  6. Step 6: Final answer
    x = 1,080.89

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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.