Home / 210.78-315.79-80.71

Finding the Fourth Proportional to 210.78, 315.79 and 80.71

Calculator

Solution

The fourth proportional to 210.78, 315.79 and 80.71 is: 120.91

Step by Step Solution

  1. Step 1: Write the proportion equation
    210.78 : 315.79 = 80.71 : x
  2. Step 2: Convert to fraction form
    210.78/315.79 = 80.71/x
  3. Step 3: Cross multiply
    210.78x = 315.79 × 80.71
  4. Step 4: Simplify right side
    210.78x = 25,486.42
  5. Step 5: Solve for x
    x = 25,486.42/210.78
  6. Step 6: Final answer
    x = 120.91

Related Problems

Find fourth proportional to 105.39, 157.89 and 40.35
Half scale
Find fourth proportional to 421.56, 631.58 and 161.42
Double scale
Find fourth proportional to 211.78, 317.29 and 81.71
Similar ratio
Find fourth proportional to 316.17, 473.68 and 121.06
1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.