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Finding the Fourth Proportional to 92.80, 128.04 and 65.16

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Solution

The fourth proportional to 92.80, 128.04 and 65.16 is: 89.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    92.80 : 128.04 = 65.16 : x
  2. Step 2: Convert to fraction form
    92.80/128.04 = 65.16/x
  3. Step 3: Cross multiply
    92.80x = 128.04 × 65.16
  4. Step 4: Simplify right side
    92.80x = 8,343.09
  5. Step 5: Solve for x
    x = 8,343.09/92.80
  6. Step 6: Final answer
    x = 89.90

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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.