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Finding the Fourth Proportional to 991.60, 1,487.25 and 261.22

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Solution

The fourth proportional to 991.60, 1,487.25 and 261.22 is: 391.79

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.60 : 1,487.25 = 261.22 : x
  2. Step 2: Convert to fraction form
    991.60/1,487.25 = 261.22/x
  3. Step 3: Cross multiply
    991.60x = 1,487.25 × 261.22
  4. Step 4: Simplify right side
    991.60x = 388,499.45
  5. Step 5: Solve for x
    x = 388,499.45/991.60
  6. Step 6: Final answer
    x = 391.79

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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.