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Finding the Fourth Proportional to 1,379.90, 2,069.59 and 721.07

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Solution

The fourth proportional to 1,379.90, 2,069.59 and 721.07 is: 1,081.46

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,379.90 : 2,069.59 = 721.07 : x
  2. Step 2: Convert to fraction form
    1,379.90/2,069.59 = 721.07/x
  3. Step 3: Cross multiply
    1,379.90x = 2,069.59 × 721.07
  4. Step 4: Simplify right side
    1,379.90x = 1,492,307.11
  5. Step 5: Solve for x
    x = 1,492,307.11/1,379.90
  6. Step 6: Final answer
    x = 1,081.46

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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.