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Finding the Fourth Proportional to 858.68, 1,285.84 and 721

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Solution

The fourth proportional to 858.68, 1,285.84 and 721 is: 1,079.67

Step by Step Solution

  1. Step 1: Write the proportion equation
    858.68 : 1,285.84 = 721 : x
  2. Step 2: Convert to fraction form
    858.68/1,285.84 = 721/x
  3. Step 3: Cross multiply
    858.68x = 1,285.84 × 721
  4. Step 4: Simplify right side
    858.68x = 927,090.64
  5. Step 5: Solve for x
    x = 927,090.64/858.68
  6. Step 6: Final answer
    x = 1,079.67

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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.