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Finding the Fourth Proportional to 813.72, 1,221.45 and 661.49

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Solution

The fourth proportional to 813.72, 1,221.45 and 661.49 is: 992.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    813.72 : 1,221.45 = 661.49 : x
  2. Step 2: Convert to fraction form
    813.72/1,221.45 = 661.49/x
  3. Step 3: Cross multiply
    813.72x = 1,221.45 × 661.49
  4. Step 4: Simplify right side
    813.72x = 807,967.55
  5. Step 5: Solve for x
    x = 807,967.55/813.72
  6. Step 6: Final answer
    x = 992.93

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1.5x scale

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.