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Finding the Fourth Proportional to 638.70, 881.43 and 390.13

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Solution

The fourth proportional to 638.70, 881.43 and 390.13 is: 538.39

Step by Step Solution

  1. Step 1: Write the proportion equation
    638.70 : 881.43 = 390.13 : x
  2. Step 2: Convert to fraction form
    638.70/881.43 = 390.13/x
  3. Step 3: Cross multiply
    638.70x = 881.43 × 390.13
  4. Step 4: Simplify right side
    638.70x = 343,871.51
  5. Step 5: Solve for x
    x = 343,871.51/638.70
  6. Step 6: Final answer
    x = 538.39

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1.5x scale

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.