Home / 72.96-100.80-61.60

Finding the Fourth Proportional to 72.96, 100.80 and 61.60

Calculator

Solution

The fourth proportional to 72.96, 100.80 and 61.60 is: 85.11

Step by Step Solution

  1. Step 1: Write the proportion equation
    72.96 : 100.80 = 61.60 : x
  2. Step 2: Convert to fraction form
    72.96/100.80 = 61.60/x
  3. Step 3: Cross multiply
    72.96x = 100.80 × 61.60
  4. Step 4: Simplify right side
    72.96x = 6,209.28
  5. Step 5: Solve for x
    x = 6,209.28/72.96
  6. Step 6: Final answer
    x = 85.11

Related Problems

Find fourth proportional to 36.48, 50.40 and 30.80
Half scale
Find fourth proportional to 145.92, 201.60 and 123.20
Double scale
Find fourth proportional to 73.96, 102.18 and 62.60
Similar ratio
Find fourth proportional to 109.44, 151.20 and 92.40
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.