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Finding the Fourth Proportional to 1,311.60, 1,810 and 722.15

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Solution

The fourth proportional to 1,311.60, 1,810 and 722.15 is: 996.56

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,311.60 : 1,810 = 722.15 : x
  2. Step 2: Convert to fraction form
    1,311.60/1,810 = 722.15/x
  3. Step 3: Cross multiply
    1,311.60x = 1,810 × 722.15
  4. Step 4: Simplify right side
    1,311.60x = 1,307,091.50
  5. Step 5: Solve for x
    x = 1,307,091.50/1,311.60
  6. Step 6: Final answer
    x = 996.56

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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.