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Finding the Fourth Proportional to 691.21, 1,036.40 and 257.86

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Solution

The fourth proportional to 691.21, 1,036.40 and 257.86 is: 386.63

Step by Step Solution

  1. Step 1: Write the proportion equation
    691.21 : 1,036.40 = 257.86 : x
  2. Step 2: Convert to fraction form
    691.21/1,036.40 = 257.86/x
  3. Step 3: Cross multiply
    691.21x = 1,036.40 × 257.86
  4. Step 4: Simplify right side
    691.21x = 267,244.81
  5. Step 5: Solve for x
    x = 267,244.81/691.21
  6. Step 6: Final answer
    x = 386.63

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.