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Finding the Fourth Proportional to 859.74, 1,287.96 and 427.20

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Solution

The fourth proportional to 859.74, 1,287.96 and 427.20 is: 639.98

Step by Step Solution

  1. Step 1: Write the proportion equation
    859.74 : 1,287.96 = 427.20 : x
  2. Step 2: Convert to fraction form
    859.74/1,287.96 = 427.20/x
  3. Step 3: Cross multiply
    859.74x = 1,287.96 × 427.20
  4. Step 4: Simplify right side
    859.74x = 550,216.51
  5. Step 5: Solve for x
    x = 550,216.51/859.74
  6. Step 6: Final answer
    x = 639.98

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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.