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Finding the Fourth Proportional to 870.12, 1,293.98 and 842.78

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Solution

The fourth proportional to 870.12, 1,293.98 and 842.78 is: 1,253.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.12 : 1,293.98 = 842.78 : x
  2. Step 2: Convert to fraction form
    870.12/1,293.98 = 842.78/x
  3. Step 3: Cross multiply
    870.12x = 1,293.98 × 842.78
  4. Step 4: Simplify right side
    870.12x = 1,090,540.46
  5. Step 5: Solve for x
    x = 1,090,540.46/870.12
  6. Step 6: Final answer
    x = 1,253.32

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Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.