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Finding the Fourth Proportional to 1,390.74, 1,919.20 and 761.25

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Solution

The fourth proportional to 1,390.74, 1,919.20 and 761.25 is: 1,050.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,390.74 : 1,919.20 = 761.25 : x
  2. Step 2: Convert to fraction form
    1,390.74/1,919.20 = 761.25/x
  3. Step 3: Cross multiply
    1,390.74x = 1,919.20 × 761.25
  4. Step 4: Simplify right side
    1,390.74x = 1,460,989.10
  5. Step 5: Solve for x
    x = 1,460,989.10/1,390.74
  6. Step 6: Final answer
    x = 1,050.51

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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.