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Finding the Fourth Proportional to 784.65, 1,170.12 and 687.60

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Solution

The fourth proportional to 784.65, 1,170.12 and 687.60 is: 1,025.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    784.65 : 1,170.12 = 687.60 : x
  2. Step 2: Convert to fraction form
    784.65/1,170.12 = 687.60/x
  3. Step 3: Cross multiply
    784.65x = 1,170.12 × 687.60
  4. Step 4: Simplify right side
    784.65x = 804,578.90
  5. Step 5: Solve for x
    x = 804,578.90/784.65
  6. Step 6: Final answer
    x = 1,025.39

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.