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Finding the Fourth Proportional to 987.94, 1,479.58 and 781.12

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Solution

The fourth proportional to 987.94, 1,479.58 and 781.12 is: 1,169.84

Step by Step Solution

  1. Step 1: Write the proportion equation
    987.94 : 1,479.58 = 781.12 : x
  2. Step 2: Convert to fraction form
    987.94/1,479.58 = 781.12/x
  3. Step 3: Cross multiply
    987.94x = 1,479.58 × 781.12
  4. Step 4: Simplify right side
    987.94x = 1,155,729.53
  5. Step 5: Solve for x
    x = 1,155,729.53/987.94
  6. Step 6: Final answer
    x = 1,169.84

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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.