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Finding the Fourth Proportional to 291.10, 436.64 and 128.78

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Solution

The fourth proportional to 291.10, 436.64 and 128.78 is: 193.17

Step by Step Solution

  1. Step 1: Write the proportion equation
    291.10 : 436.64 = 128.78 : x
  2. Step 2: Convert to fraction form
    291.10/436.64 = 128.78/x
  3. Step 3: Cross multiply
    291.10x = 436.64 × 128.78
  4. Step 4: Simplify right side
    291.10x = 56,230.50
  5. Step 5: Solve for x
    x = 56,230.50/291.10
  6. Step 6: Final answer
    x = 193.17

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.