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Finding the Fourth Proportional to 728.12, 1,005.90 and 664.76

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Solution

The fourth proportional to 728.12, 1,005.90 and 664.76 is: 918.37

Step by Step Solution

  1. Step 1: Write the proportion equation
    728.12 : 1,005.90 = 664.76 : x
  2. Step 2: Convert to fraction form
    728.12/1,005.90 = 664.76/x
  3. Step 3: Cross multiply
    728.12x = 1,005.90 × 664.76
  4. Step 4: Simplify right side
    728.12x = 668,682.08
  5. Step 5: Solve for x
    x = 668,682.08/728.12
  6. Step 6: Final answer
    x = 918.37

Related Problems

Find fourth proportional to 364.06, 502.95 and 332.38
Half scale
Find fourth proportional to 1,456.24, 2,011.80 and 1,329.52
Double scale
Find fourth proportional to 729.12, 1,007.28 and 665.76
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.