Home / 715.82-987.78-421.05

Finding the Fourth Proportional to 715.82, 987.78 and 421.05

Calculator

Solution

The fourth proportional to 715.82, 987.78 and 421.05 is: 581.02

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.82 : 987.78 = 421.05 : x
  2. Step 2: Convert to fraction form
    715.82/987.78 = 421.05/x
  3. Step 3: Cross multiply
    715.82x = 987.78 × 421.05
  4. Step 4: Simplify right side
    715.82x = 415,904.77
  5. Step 5: Solve for x
    x = 415,904.77/715.82
  6. Step 6: Final answer
    x = 581.02

Related Problems

Find fourth proportional to 357.91, 493.89 and 210.53
Half scale
Find fourth proportional to 1,431.65, 1,975.56 and 842.10
Double scale
Find fourth proportional to 716.82, 989.16 and 422.05
Similar ratio
Find fourth proportional to 1,073.73, 1,481.67 and 631.58
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.