Question: Wind Chill - Question I

Comment on Wind Chill - Question I

Hey Brent

I fail to understand that part (b) is true
The question asks atleast 3, but city E not necessarily faces the risk
So there would be either 2 or 3 cities where frostbite will occur
Since we cannot say with certainity that in "atleast' 3 cities frostbite will occur, shouldn't the statement be false?
gmat-admin's picture

But city E definitely has a risk of frostbite.
The air temperature is 0 degrees
The wind is 20 mph
These values correspond with a PERCEIVED temperature of -22 degrees, which is in the "frostbite zone."

When answering part (c), I followed another approach and my answer came out to be false

I checked the columns of 0 and -5 degrees, as only they have a range that might include perceived temperature of -25 degrees
For -5 degrees temp column, I checked that -25 lies somewhere between -22 and -26 and since these perceived temp. have wind speed 10 and 15 mph resp. So -25 would have a wind speed between these two but can't be 20
Similarly for 0 degrees temp column, I checked that -25 lies somewhere between -24 and -26 and since these perc. temp. have wind speed 25 and 30 mph resp. So -25 would have a wind speed between these two but can't be 20.
So, the statement is false.

Can you please help me out as to where am I wrong?
gmat-admin's picture

Hi Kamaksi,

You are operating on the principle that the actual air temperature must be either 0 or -5 degrees. This is not true. The air temperature can also be 1 degree or 2.3 degrees, etc.

Since we don't have a separate column for every possible temperature, it's easier to focus on the given wind speed of 20 mph.

At 4:20 in the video, we highlight the row corresponding to a wind speed of 20 mph.

If the air temperature is 0 degrees, then the perceived temperature is -22 degrees. If the air temperature is -5 degrees, then the perceived temperature is -29 degrees.

So, if the wind speed is 20 mph and the air temperature is BETWEEN 0 degrees and -5 degrees, and the perceived temperature will be BETWEEN -22 degrees and -29 degrees.

So, at some temperature between 0 degrees and -5 degrees, the perceived temperature will be -25 degrees.

Does that help?

Thanks a lot Brent
Your videos are amazing!
gmat-admin's picture

I'm glad you like them!

so you mean each point here in the table is the perceived temperature? i got it confused with frostbite.
frost bite is only indicated by color.
gmat-admin's picture

That's correct; each numeric entry in the boxes represents perceived temperature. At the beginning of the video, the text next to the table notes this.

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