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Finding the Fourth Proportional to 644.88, 890.40 and 438

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Solution

The fourth proportional to 644.88, 890.40 and 438 is: 604.76

Step by Step Solution

  1. Step 1: Write the proportion equation
    644.88 : 890.40 = 438 : x
  2. Step 2: Convert to fraction form
    644.88/890.40 = 438/x
  3. Step 3: Cross multiply
    644.88x = 890.40 × 438
  4. Step 4: Simplify right side
    644.88x = 389,995.20
  5. Step 5: Solve for x
    x = 389,995.20/644.88
  6. Step 6: Final answer
    x = 604.76

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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.