Home / 39.98-55.20-30.80

Finding the Fourth Proportional to 39.98, 55.20 and 30.80

Calculator

Solution

The fourth proportional to 39.98, 55.20 and 30.80 is: 42.53

Step by Step Solution

  1. Step 1: Write the proportion equation
    39.98 : 55.20 = 30.80 : x
  2. Step 2: Convert to fraction form
    39.98/55.20 = 30.80/x
  3. Step 3: Cross multiply
    39.98x = 55.20 × 30.80
  4. Step 4: Simplify right side
    39.98x = 1,700.16
  5. Step 5: Solve for x
    x = 1,700.16/39.98
  6. Step 6: Final answer
    x = 42.53

Related Problems

Find fourth proportional to 19.99, 27.60 and 15.40
Half scale
Find fourth proportional to 79.96, 110.40 and 61.60
Double scale
Find fourth proportional to 40.98, 56.58 and 31.80
Similar ratio
Find fourth proportional to 59.97, 82.80 and 46.20
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.