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Finding the Fourth Proportional to 1,290.34, 1,931.91 and 856.90

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Solution

The fourth proportional to 1,290.34, 1,931.91 and 856.90 is: 1,282.96

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,290.34 : 1,931.91 = 856.90 : x
  2. Step 2: Convert to fraction form
    1,290.34/1,931.91 = 856.90/x
  3. Step 3: Cross multiply
    1,290.34x = 1,931.91 × 856.90
  4. Step 4: Simplify right side
    1,290.34x = 1,655,453.68
  5. Step 5: Solve for x
    x = 1,655,453.68/1,290.34
  6. Step 6: Final answer
    x = 1,282.96

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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.