Home / 978.80-1,351.11-647.68

Finding the Fourth Proportional to 978.80, 1,351.11 and 647.68

Calculator

Solution

The fourth proportional to 978.80, 1,351.11 and 647.68 is: 894.04

Step by Step Solution

  1. Step 1: Write the proportion equation
    978.80 : 1,351.11 = 647.68 : x
  2. Step 2: Convert to fraction form
    978.80/1,351.11 = 647.68/x
  3. Step 3: Cross multiply
    978.80x = 1,351.11 × 647.68
  4. Step 4: Simplify right side
    978.80x = 875,086.92
  5. Step 5: Solve for x
    x = 875,086.92/978.80
  6. Step 6: Final answer
    x = 894.04

Related Problems

Find fourth proportional to 489.40, 675.56 and 323.84
Half scale
Find fourth proportional to 1,957.60, 2,702.22 and 1,295.36
Double scale
Find fourth proportional to 979.80, 1,352.49 and 648.68
Similar ratio
Find fourth proportional to 1,468.20, 2,026.67 and 971.52
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.