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Finding the Fourth Proportional to 1,213.56, 1,671.30 and 991.80

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Solution

The fourth proportional to 1,213.56, 1,671.30 and 991.80 is: 1,365.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,213.56 : 1,671.30 = 991.80 : x
  2. Step 2: Convert to fraction form
    1,213.56/1,671.30 = 991.80/x
  3. Step 3: Cross multiply
    1,213.56x = 1,671.30 × 991.80
  4. Step 4: Simplify right side
    1,213.56x = 1,657,595.34
  5. Step 5: Solve for x
    x = 1,657,595.34/1,213.56
  6. Step 6: Final answer
    x = 1,365.89

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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.