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Finding the Fourth Proportional to 991.12, 1,486.80 and 478

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Solution

The fourth proportional to 991.12, 1,486.80 and 478 is: 717.06

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.12 : 1,486.80 = 478 : x
  2. Step 2: Convert to fraction form
    991.12/1,486.80 = 478/x
  3. Step 3: Cross multiply
    991.12x = 1,486.80 × 478
  4. Step 4: Simplify right side
    991.12x = 710,690.40
  5. Step 5: Solve for x
    x = 710,690.40/991.12
  6. Step 6: Final answer
    x = 717.06

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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.