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Finding the Fourth Proportional to 93.90, 139.76 and 90.78

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Solution

The fourth proportional to 93.90, 139.76 and 90.78 is: 135.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    93.90 : 139.76 = 90.78 : x
  2. Step 2: Convert to fraction form
    93.90/139.76 = 90.78/x
  3. Step 3: Cross multiply
    93.90x = 139.76 × 90.78
  4. Step 4: Simplify right side
    93.90x = 12,686.96
  5. Step 5: Solve for x
    x = 12,686.96/93.90
  6. Step 6: Final answer
    x = 135.11

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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.