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Finding the Fourth Proportional to 870.72, 1,201.44 and 638.40

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Solution

The fourth proportional to 870.72, 1,201.44 and 638.40 is: 880.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.72 : 1,201.44 = 638.40 : x
  2. Step 2: Convert to fraction form
    870.72/1,201.44 = 638.40/x
  3. Step 3: Cross multiply
    870.72x = 1,201.44 × 638.40
  4. Step 4: Simplify right side
    870.72x = 766,999.30
  5. Step 5: Solve for x
    x = 766,999.30/870.72
  6. Step 6: Final answer
    x = 880.88

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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.