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Finding the Fourth Proportional to 1,221.28, 1,685.28 and 690.25

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Solution

The fourth proportional to 1,221.28, 1,685.28 and 690.25 is: 952.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,221.28 : 1,685.28 = 690.25 : x
  2. Step 2: Convert to fraction form
    1,221.28/1,685.28 = 690.25/x
  3. Step 3: Cross multiply
    1,221.28x = 1,685.28 × 690.25
  4. Step 4: Simplify right side
    1,221.28x = 1,163,264.52
  5. Step 5: Solve for x
    x = 1,163,264.52/1,221.28
  6. Step 6: Final answer
    x = 952.50

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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.