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Finding the Fourth Proportional to 405.51, 555.74 and 391.65

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Solution

The fourth proportional to 405.51, 555.74 and 391.65 is: 536.74

Step by Step Solution

  1. Step 1: Write the proportion equation
    405.51 : 555.74 = 391.65 : x
  2. Step 2: Convert to fraction form
    405.51/555.74 = 391.65/x
  3. Step 3: Cross multiply
    405.51x = 555.74 × 391.65
  4. Step 4: Simplify right side
    405.51x = 217,653.61
  5. Step 5: Solve for x
    x = 217,653.61/405.51
  6. Step 6: Final answer
    x = 536.74

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Why These Related Problems?

These problems maintain the same ratio (1.37) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.