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Finding the Fourth Proportional to 720.90, 1,081.35 and 258.81

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Solution

The fourth proportional to 720.90, 1,081.35 and 258.81 is: 388.22

Step by Step Solution

  1. Step 1: Write the proportion equation
    720.90 : 1,081.35 = 258.81 : x
  2. Step 2: Convert to fraction form
    720.90/1,081.35 = 258.81/x
  3. Step 3: Cross multiply
    720.90x = 1,081.35 × 258.81
  4. Step 4: Simplify right side
    720.90x = 279,864.19
  5. Step 5: Solve for x
    x = 279,864.19/720.90
  6. Step 6: Final answer
    x = 388.22

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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.