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Finding the Fourth Proportional to 685.21, 1,028.87 and 412.51

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Solution

The fourth proportional to 685.21, 1,028.87 and 412.51 is: 619.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.21 : 1,028.87 = 412.51 : x
  2. Step 2: Convert to fraction form
    685.21/1,028.87 = 412.51/x
  3. Step 3: Cross multiply
    685.21x = 1,028.87 × 412.51
  4. Step 4: Simplify right side
    685.21x = 424,419.16
  5. Step 5: Solve for x
    x = 424,419.16/685.21
  6. Step 6: Final answer
    x = 619.40

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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.