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Finding the Fourth Proportional to 718.50, 991.64 and 438.90

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Solution

The fourth proportional to 718.50, 991.64 and 438.90 is: 605.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    718.50 : 991.64 = 438.90 : x
  2. Step 2: Convert to fraction form
    718.50/991.64 = 438.90/x
  3. Step 3: Cross multiply
    718.50x = 991.64 × 438.90
  4. Step 4: Simplify right side
    718.50x = 435,229.21
  5. Step 5: Solve for x
    x = 435,229.21/718.50
  6. Step 6: Final answer
    x = 605.74

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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.