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Finding the Fourth Proportional to 1,225.21, 1,690.83 and 665.72

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Solution

The fourth proportional to 1,225.21, 1,690.83 and 665.72 is: 918.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,225.21 : 1,690.83 = 665.72 : x
  2. Step 2: Convert to fraction form
    1,225.21/1,690.83 = 665.72/x
  3. Step 3: Cross multiply
    1,225.21x = 1,690.83 × 665.72
  4. Step 4: Simplify right side
    1,225.21x = 1,125,619.35
  5. Step 5: Solve for x
    x = 1,125,619.35/1,225.21
  6. Step 6: Final answer
    x = 918.72

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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.