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Finding the Fourth Proportional to 1,225.10, 1,690.63 and 665.55

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Solution

The fourth proportional to 1,225.10, 1,690.63 and 665.55 is: 918.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,225.10 : 1,690.63 = 665.55 : x
  2. Step 2: Convert to fraction form
    1,225.10/1,690.63 = 665.55/x
  3. Step 3: Cross multiply
    1,225.10x = 1,690.63 × 665.55
  4. Step 4: Simplify right side
    1,225.10x = 1,125,197.13
  5. Step 5: Solve for x
    x = 1,125,197.13/1,225.10
  6. Step 6: Final answer
    x = 918.45

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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.