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Finding the Fourth Proportional to 931.47, 1,399.73 and 687.21

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Solution

The fourth proportional to 931.47, 1,399.73 and 687.21 is: 1,032.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    931.47 : 1,399.73 = 687.21 : x
  2. Step 2: Convert to fraction form
    931.47/1,399.73 = 687.21/x
  3. Step 3: Cross multiply
    931.47x = 1,399.73 × 687.21
  4. Step 4: Simplify right side
    931.47x = 961,905.02
  5. Step 5: Solve for x
    x = 961,905.02/931.47
  6. Step 6: Final answer
    x = 1,032.67

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.