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Finding the Fourth Proportional to 871.68, 1,298.40 and 840.64

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Solution

The fourth proportional to 871.68, 1,298.40 and 840.64 is: 1,252.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    871.68 : 1,298.40 = 840.64 : x
  2. Step 2: Convert to fraction form
    871.68/1,298.40 = 840.64/x
  3. Step 3: Cross multiply
    871.68x = 1,298.40 × 840.64
  4. Step 4: Simplify right side
    871.68x = 1,091,486.98
  5. Step 5: Solve for x
    x = 1,091,486.98/871.68
  6. Step 6: Final answer
    x = 1,252.16

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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.