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Finding the Fourth Proportional to 786.69, 1,086.21 and 639.63

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Solution

The fourth proportional to 786.69, 1,086.21 and 639.63 is: 883.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.69 : 1,086.21 = 639.63 : x
  2. Step 2: Convert to fraction form
    786.69/1,086.21 = 639.63/x
  3. Step 3: Cross multiply
    786.69x = 1,086.21 × 639.63
  4. Step 4: Simplify right side
    786.69x = 694,772.50
  5. Step 5: Solve for x
    x = 694,772.50/786.69
  6. Step 6: Final answer
    x = 883.16

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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.