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Finding the Fourth Proportional to 685.96, 946.76 and 391.20

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Solution

The fourth proportional to 685.96, 946.76 and 391.20 is: 539.93

Step by Step Solution

  1. Step 1: Write the proportion equation
    685.96 : 946.76 = 391.20 : x
  2. Step 2: Convert to fraction form
    685.96/946.76 = 391.20/x
  3. Step 3: Cross multiply
    685.96x = 946.76 × 391.20
  4. Step 4: Simplify right side
    685.96x = 370,372.51
  5. Step 5: Solve for x
    x = 370,372.51/685.96
  6. Step 6: Final answer
    x = 539.93

Related Problems

Find fourth proportional to 342.98, 473.38 and 195.60
Half scale
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Double scale
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Similar ratio
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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.