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Finding the Fourth Proportional to 987.72, 1,478.36 and 727.61

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Solution

The fourth proportional to 987.72, 1,478.36 and 727.61 is: 1,089.05

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.72 : 1,478.36 = 727.61 : x
  2. Step 2: Convert to fraction form
    987.72/1,478.36 = 727.61/x
  3. Step 3: Cross multiply
    987.72x = 1,478.36 × 727.61
  4. Step 4: Simplify right side
    987.72x = 1,075,669.58
  5. Step 5: Solve for x
    x = 1,075,669.58/987.72
  6. Step 6: Final answer
    x = 1,089.05

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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.