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Finding the Fourth Proportional to 919.71, 1,269.36 and 521.40

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Solution

The fourth proportional to 919.71, 1,269.36 and 521.40 is: 719.62

Step by Step Solution

  1. Step 1: Write the proportion equation
    919.71 : 1,269.36 = 521.40 : x
  2. Step 2: Convert to fraction form
    919.71/1,269.36 = 521.40/x
  3. Step 3: Cross multiply
    919.71x = 1,269.36 × 521.40
  4. Step 4: Simplify right side
    919.71x = 661,837.96
  5. Step 5: Solve for x
    x = 661,837.96/919.71
  6. Step 6: Final answer
    x = 719.62

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Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.