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Finding the Fourth Proportional to 1,220.78, 1,684.67 and 661.25

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Solution

The fourth proportional to 1,220.78, 1,684.67 and 661.25 is: 912.52

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,220.78 : 1,684.67 = 661.25 : x
  2. Step 2: Convert to fraction form
    1,220.78/1,684.67 = 661.25/x
  3. Step 3: Cross multiply
    1,220.78x = 1,684.67 × 661.25
  4. Step 4: Simplify right side
    1,220.78x = 1,113,982.26
  5. Step 5: Solve for x
    x = 1,113,982.26/1,220.78
  6. Step 6: Final answer
    x = 912.52

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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.