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Finding the Fourth Proportional to 1,421.90, 2,134.05 and 643.10

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Solution

The fourth proportional to 1,421.90, 2,134.05 and 643.10 is: 965.19

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,421.90 : 2,134.05 = 643.10 : x
  2. Step 2: Convert to fraction form
    1,421.90/2,134.05 = 643.10/x
  3. Step 3: Cross multiply
    1,421.90x = 2,134.05 × 643.10
  4. Step 4: Simplify right side
    1,421.90x = 1,372,407.56
  5. Step 5: Solve for x
    x = 1,372,407.56/1,421.90
  6. Step 6: Final answer
    x = 965.19

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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.