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Finding the Fourth Proportional to 987.79, 1,360.13 and 862.72

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Solution

The fourth proportional to 987.79, 1,360.13 and 862.72 is: 1,187.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.79 : 1,360.13 = 862.72 : x
  2. Step 2: Convert to fraction form
    987.79/1,360.13 = 862.72/x
  3. Step 3: Cross multiply
    987.79x = 1,360.13 × 862.72
  4. Step 4: Simplify right side
    987.79x = 1,173,408.49
  5. Step 5: Solve for x
    x = 1,173,408.49/987.79
  6. Step 6: Final answer
    x = 1,187.91

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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.