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Finding the Fourth Proportional to 920.75, 1,381.16 and 407.75

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Solution

The fourth proportional to 920.75, 1,381.16 and 407.75 is: 611.64

Step by Step Solution

  1. Step 1: Write the proportion equation
    920.75 : 1,381.16 = 407.75 : x
  2. Step 2: Convert to fraction form
    920.75/1,381.16 = 407.75/x
  3. Step 3: Cross multiply
    920.75x = 1,381.16 × 407.75
  4. Step 4: Simplify right side
    920.75x = 563,165.95
  5. Step 5: Solve for x
    x = 563,165.95/920.75
  6. Step 6: Final answer
    x = 611.64

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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.