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Finding the Fourth Proportional to 1,319.21, 1,978.95 and 669.77

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Solution

The fourth proportional to 1,319.21, 1,978.95 and 669.77 is: 1,004.72

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,319.21 : 1,978.95 = 669.77 : x
  2. Step 2: Convert to fraction form
    1,319.21/1,978.95 = 669.77/x
  3. Step 3: Cross multiply
    1,319.21x = 1,978.95 × 669.77
  4. Step 4: Simplify right side
    1,319.21x = 1,325,441.34
  5. Step 5: Solve for x
    x = 1,325,441.34/1,319.21
  6. Step 6: Final answer
    x = 1,004.72

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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.