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Finding the Fourth Proportional to 987.81, 1,480.10 and 728.34

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Solution

The fourth proportional to 987.81, 1,480.10 and 728.34 is: 1,091.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.81 : 1,480.10 = 728.34 : x
  2. Step 2: Convert to fraction form
    987.81/1,480.10 = 728.34/x
  3. Step 3: Cross multiply
    987.81x = 1,480.10 × 728.34
  4. Step 4: Simplify right side
    987.81x = 1,078,012.39
  5. Step 5: Solve for x
    x = 1,078,012.39/987.81
  6. Step 6: Final answer
    x = 1,091.32

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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.