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Finding the Fourth Proportional to 642.76, 887.15 and 421.63

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Solution

The fourth proportional to 642.76, 887.15 and 421.63 is: 581.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    642.76 : 887.15 = 421.63 : x
  2. Step 2: Convert to fraction form
    642.76/887.15 = 421.63/x
  3. Step 3: Cross multiply
    642.76x = 887.15 × 421.63
  4. Step 4: Simplify right side
    642.76x = 374,049.05
  5. Step 5: Solve for x
    x = 374,049.05/642.76
  6. Step 6: Final answer
    x = 581.94

Related Problems

Find fourth proportional to 321.38, 443.58 and 210.82
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Double scale
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1.5x scale

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.