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Finding the Fourth Proportional to 861, 1,291.50 and 253

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Solution

The fourth proportional to 861, 1,291.50 and 253 is: 379.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    861 : 1,291.50 = 253 : x
  2. Step 2: Convert to fraction form
    861/1,291.50 = 253/x
  3. Step 3: Cross multiply
    861x = 1,291.50 × 253
  4. Step 4: Simplify right side
    861x = 326,749.50
  5. Step 5: Solve for x
    x = 326,749.50/861
  6. Step 6: Final answer
    x = 379.50

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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.