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Finding the Fourth Proportional to 1,313.90, 1,969.22 and 728.40

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Solution

The fourth proportional to 1,313.90, 1,969.22 and 728.40 is: 1,091.70

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,313.90 : 1,969.22 = 728.40 : x
  2. Step 2: Convert to fraction form
    1,313.90/1,969.22 = 728.40/x
  3. Step 3: Cross multiply
    1,313.90x = 1,969.22 × 728.40
  4. Step 4: Simplify right side
    1,313.90x = 1,434,381.67
  5. Step 5: Solve for x
    x = 1,434,381.67/1,313.90
  6. Step 6: Final answer
    x = 1,091.70

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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.