Question

a skier ascends a ski lift, skis down the mountain, and then stops. how long did they take to ski down the mountain, before coming to a stop? 30 seconds 50 seconds 20 seconds 10 seconds

Explanation:

Step1: Identify the time intervals for skiing down

The graph shows the skier's altitude over time. The descent (skiing down) starts at 30 minutes (altitude 80 feet) and ends at 50 minutes (altitude 0 feet).

Step2: Calculate the time taken for descent

Use the formula \(t = t_{end}-t_{start}\). Here, \(t_{start} = 30\) and \(t_{end}=50\). So \(t = 50 - 30=20\) minutes. But wait, looking at the options, they are in seconds. Wait no - wait the x - axis is in minutes. Wait no, re - check: The x - axis is labeled "Time (minutes)", but the options are in seconds. Wait no, mistake in problem reading. Wait the x - axis has gridlines. Each gridline is 5 units (since from 0 to 10 is 2 gridlines). The descent starts at \(x = 30\) and ends at \(x = 50\). The time taken for skiing down is \(50 - 30=20\) (unit is minutes? No, no - wait no! Wait the options are in seconds. Wait no - the problem is misread. Wait the x - axis: each small grid is 5 minutes? No, wait the x - axis: from 0 to 10 is 2 grid - intervals (each grid - interval is 5 minutes). But no, wait the question is "how long did they take to ski down". Looking at the graph: the ascent is from \(t = 0\) to \(t = 30\), descent is from \(t = 30\) to \(t = 50\). But the options are in seconds. Wait no - it's a misprint. Wait no, the y - axis is altitude (feet), x - axis is time (minutes). But the options are 30 seconds, 50 seconds, 20 seconds, 10 seconds. Wait no - it's a mistake in units in the problem (maybe a typo, x - axis is in seconds). If we assume x - axis is in seconds (despite label), then from \(t = 30\) to \(t = 50\) (subtracting), the time is \(50 - 30=20\) seconds.

Answer:

20 seconds