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Finding the Fourth Proportional to 690.72, 1,036.32 and 280.32

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Solution

The fourth proportional to 690.72, 1,036.32 and 280.32 is: 420.58

Step by Step Solution

  1. Step 1: Write the proportion equation
    690.72 : 1,036.32 = 280.32 : x
  2. Step 2: Convert to fraction form
    690.72/1,036.32 = 280.32/x
  3. Step 3: Cross multiply
    690.72x = 1,036.32 × 280.32
  4. Step 4: Simplify right side
    690.72x = 290,501.22
  5. Step 5: Solve for x
    x = 290,501.22/690.72
  6. Step 6: Final answer
    x = 420.58

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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.