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Finding the Fourth Proportional to 991.21, 1,487.96 and 580.64

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Solution

The fourth proportional to 991.21, 1,487.96 and 580.64 is: 871.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    991.21 : 1,487.96 = 580.64 : x
  2. Step 2: Convert to fraction form
    991.21/1,487.96 = 580.64/x
  3. Step 3: Cross multiply
    991.21x = 1,487.96 × 580.64
  4. Step 4: Simplify right side
    991.21x = 863,969.09
  5. Step 5: Solve for x
    x = 863,969.09/991.21
  6. Step 6: Final answer
    x = 871.63

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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.