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Finding the Fourth Proportional to 92.90, 128.23 and 61.80

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Solution

The fourth proportional to 92.90, 128.23 and 61.80 is: 85.31

Step by Step Solution

  1. Step 1: Write the proportion equation
    92.90 : 128.23 = 61.80 : x
  2. Step 2: Convert to fraction form
    92.90/128.23 = 61.80/x
  3. Step 3: Cross multiply
    92.90x = 128.23 × 61.80
  4. Step 4: Simplify right side
    92.90x = 7,924.46
  5. Step 5: Solve for x
    x = 7,924.46/92.90
  6. Step 6: Final answer
    x = 85.31

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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.