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Finding the Fourth Proportional to 1,245.87, 1,719.40 and 686.45

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Solution

The fourth proportional to 1,245.87, 1,719.40 and 686.45 is: 947.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,245.87 : 1,719.40 = 686.45 : x
  2. Step 2: Convert to fraction form
    1,245.87/1,719.40 = 686.45/x
  3. Step 3: Cross multiply
    1,245.87x = 1,719.40 × 686.45
  4. Step 4: Simplify right side
    1,245.87x = 1,180,282.13
  5. Step 5: Solve for x
    x = 1,180,282.13/1,245.87
  6. Step 6: Final answer
    x = 947.36

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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.