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Finding the Fourth Proportional to 1,115.45, 1,539.53 and 643.65

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Solution

The fourth proportional to 1,115.45, 1,539.53 and 643.65 is: 888.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,115.45 : 1,539.53 = 643.65 : x
  2. Step 2: Convert to fraction form
    1,115.45/1,539.53 = 643.65/x
  3. Step 3: Cross multiply
    1,115.45x = 1,539.53 × 643.65
  4. Step 4: Simplify right side
    1,115.45x = 990,910.79
  5. Step 5: Solve for x
    x = 990,910.79/1,115.45
  6. Step 6: Final answer
    x = 888.35

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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.