Home / 879.76-1,209.96-721.20

Finding the Fourth Proportional to 879.76, 1,209.96 and 721.20

Calculator

Solution

The fourth proportional to 879.76, 1,209.96 and 721.20 is: 991.89

Step by Step Solution

  1. Step 1: Write the proportion equation
    879.76 : 1,209.96 = 721.20 : x
  2. Step 2: Convert to fraction form
    879.76/1,209.96 = 721.20/x
  3. Step 3: Cross multiply
    879.76x = 1,209.96 × 721.20
  4. Step 4: Simplify right side
    879.76x = 872,623.15
  5. Step 5: Solve for x
    x = 872,623.15/879.76
  6. Step 6: Final answer
    x = 991.89

Related Problems

Find fourth proportional to 439.88, 604.98 and 360.60
Half scale
Find fourth proportional to 1,759.52, 2,419.92 and 1,442.40
Double scale
Find fourth proportional to 880.76, 1,211.34 and 722.20
Similar ratio
Find fourth proportional to 1,319.64, 1,814.94 and 1,081.80
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.