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Finding the Fourth Proportional to 643.42, 887.96 and 485.77

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Solution

The fourth proportional to 643.42, 887.96 and 485.77 is: 670.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    643.42 : 887.96 = 485.77 : x
  2. Step 2: Convert to fraction form
    643.42/887.96 = 485.77/x
  3. Step 3: Cross multiply
    643.42x = 887.96 × 485.77
  4. Step 4: Simplify right side
    643.42x = 431,344.33
  5. Step 5: Solve for x
    x = 431,344.33/643.42
  6. Step 6: Final answer
    x = 670.40

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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.