Compute the Arc Length of a Curve
Company: Goldman Sachs
Role: Data Scientist
Category: Statistics & Math
Difficulty: easy
Interview Round: Online Assessment
# Compute the Arc Length of a Curve
Find the arc length of `y = (2/3)x^(3/2) + 1` over `0 <= x <= 1`. Show the derivative, the arc-length integral, and the exact final value.
### Constraints & Assumptions
- Use the ordinary Euclidean arc-length formula for a differentiable graph.
- The fractional power denotes the nonnegative real value on this interval.
### Clarifying Questions to Ask
- Is an exact expression sufficient, or is a decimal approximation also wanted?
- Should the setup be derived from the general arc-length formula?
```hint Differentiate before simplifying
The coefficient is chosen so the square of the derivative makes the integrand simple.
```
### What a Strong Answer Covers
- Correct derivative on the interval.
- Correct substitution into `sqrt(1 + (dy/dx)^2)`.
- Accurate evaluation of the definite integral.
- A quick plausibility check against the straight-line distance.
### Follow-up Questions
- How would the result change over `0 <= x <= a`?
- Why must arc length be at least the distance between the endpoints?
Quick Answer: Derive the exact arc length of y = (2/3)x^(3/2) + 1 on [0, 1], showing the derivative, integral setup, and evaluation.