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Finding the Fourth Proportional to 875.25, 1,208.25 and 642.78

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Solution

The fourth proportional to 875.25, 1,208.25 and 642.78 is: 887.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    875.25 : 1,208.25 = 642.78 : x
  2. Step 2: Convert to fraction form
    875.25/1,208.25 = 642.78/x
  3. Step 3: Cross multiply
    875.25x = 1,208.25 × 642.78
  4. Step 4: Simplify right side
    875.25x = 776,638.94
  5. Step 5: Solve for x
    x = 776,638.94/875.25
  6. Step 6: Final answer
    x = 887.33

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Half scale
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Double scale
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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.