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Finding the Fourth Proportional to 1,287.62, 1,776.95 and 720.50

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Solution

The fourth proportional to 1,287.62, 1,776.95 and 720.50 is: 994.30

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.62 : 1,776.95 = 720.50 : x
  2. Step 2: Convert to fraction form
    1,287.62/1,776.95 = 720.50/x
  3. Step 3: Cross multiply
    1,287.62x = 1,776.95 × 720.50
  4. Step 4: Simplify right side
    1,287.62x = 1,280,279.99
  5. Step 5: Solve for x
    x = 1,280,279.99/1,287.62
  6. Step 6: Final answer
    x = 994.30

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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.