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Finding the Fourth Proportional to 948.39, 1,421.48 and 428.65

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Solution

The fourth proportional to 948.39, 1,421.48 and 428.65 is: 642.48

Step by Step Solution

  1. Step 1: Write the proportion equation
    948.39 : 1,421.48 = 428.65 : x
  2. Step 2: Convert to fraction form
    948.39/1,421.48 = 428.65/x
  3. Step 3: Cross multiply
    948.39x = 1,421.48 × 428.65
  4. Step 4: Simplify right side
    948.39x = 609,315.26
  5. Step 5: Solve for x
    x = 609,315.26/948.39
  6. Step 6: Final answer
    x = 642.48

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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.