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Finding the Fourth Proportional to 981.42, 1,353.21 and 666.43

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Solution

The fourth proportional to 981.42, 1,353.21 and 666.43 is: 918.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.42 : 1,353.21 = 666.43 : x
  2. Step 2: Convert to fraction form
    981.42/1,353.21 = 666.43/x
  3. Step 3: Cross multiply
    981.42x = 1,353.21 × 666.43
  4. Step 4: Simplify right side
    981.42x = 901,813.86
  5. Step 5: Solve for x
    x = 901,813.86/981.42
  6. Step 6: Final answer
    x = 918.89

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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.