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Finding the Fourth Proportional to 93.21, 128.70 and 74.90

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Solution

The fourth proportional to 93.21, 128.70 and 74.90 is: 103.41

Step by Step Solution

  1. Step 1: Write the proportion equation
    93.21 : 128.70 = 74.90 : x
  2. Step 2: Convert to fraction form
    93.21/128.70 = 74.90/x
  3. Step 3: Cross multiply
    93.21x = 128.70 × 74.90
  4. Step 4: Simplify right side
    93.21x = 9,638.99
  5. Step 5: Solve for x
    x = 9,638.99/93.21
  6. Step 6: Final answer
    x = 103.41

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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.