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Finding the Fourth Proportional to 485.64, 669.78 and 311.22

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Solution

The fourth proportional to 485.64, 669.78 and 311.22 is: 429.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    485.64 : 669.78 = 311.22 : x
  2. Step 2: Convert to fraction form
    485.64/669.78 = 311.22/x
  3. Step 3: Cross multiply
    485.64x = 669.78 × 311.22
  4. Step 4: Simplify right side
    485.64x = 208,448.93
  5. Step 5: Solve for x
    x = 208,448.93/485.64
  6. Step 6: Final answer
    x = 429.23

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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.