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Finding the Fourth Proportional to 981.78, 1,354.77 and 688.02

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Solution

The fourth proportional to 981.78, 1,354.77 and 688.02 is: 949.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    981.78 : 1,354.77 = 688.02 : x
  2. Step 2: Convert to fraction form
    981.78/1,354.77 = 688.02/x
  3. Step 3: Cross multiply
    981.78x = 1,354.77 × 688.02
  4. Step 4: Simplify right side
    981.78x = 932,108.86
  5. Step 5: Solve for x
    x = 932,108.86/981.78
  6. Step 6: Final answer
    x = 949.41

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1.5x scale

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.