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Finding the Fourth Proportional to 1,420.39, 2,130.54 and 690.45

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Solution

The fourth proportional to 1,420.39, 2,130.54 and 690.45 is: 1,035.65

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,420.39 : 2,130.54 = 690.45 : x
  2. Step 2: Convert to fraction form
    1,420.39/2,130.54 = 690.45/x
  3. Step 3: Cross multiply
    1,420.39x = 2,130.54 × 690.45
  4. Step 4: Simplify right side
    1,420.39x = 1,471,031.34
  5. Step 5: Solve for x
    x = 1,471,031.34/1,420.39
  6. Step 6: Final answer
    x = 1,035.65

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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.