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Finding the Fourth Proportional to 918.86, 1,268.01 and 499.21

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Solution

The fourth proportional to 918.86, 1,268.01 and 499.21 is: 688.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    918.86 : 1,268.01 = 499.21 : x
  2. Step 2: Convert to fraction form
    918.86/1,268.01 = 499.21/x
  3. Step 3: Cross multiply
    918.86x = 1,268.01 × 499.21
  4. Step 4: Simplify right side
    918.86x = 633,000.10
  5. Step 5: Solve for x
    x = 633,000.10/918.86
  6. Step 6: Final answer
    x = 688.90

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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.