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Finding the Fourth Proportional to 661.60, 912.88 and 399.61

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Solution

The fourth proportional to 661.60, 912.88 and 399.61 is: 551.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    661.60 : 912.88 = 399.61 : x
  2. Step 2: Convert to fraction form
    661.60/912.88 = 399.61/x
  3. Step 3: Cross multiply
    661.60x = 912.88 × 399.61
  4. Step 4: Simplify right side
    661.60x = 364,795.98
  5. Step 5: Solve for x
    x = 364,795.98/661.60
  6. Step 6: Final answer
    x = 551.38

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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.