Hey could someone show me the calculation to get this answer?

Hi!

Q3 = 75% of people have a heart rate of 165 or lower

so remaining 25% of people have a heart rate above 165

Propability:

1/4 * 1/4 * 1/4 * 3/4 = 3/256

1/4 * 1/4 * 3/4 * 1/4 = 3/256

1/4 * 3/4 * 1/4 * 1/4 = 3/256

3/4 * 1/4 * 1/4 * 1/4 = 3/256

sum = 12/256

BUT THEREâ€™S A TRAP!

the question says â€śAT LEAST 3 of them have a high heart rateâ€ť, so we must also count for the possibility that ALL FOUR have high heart rate:

1/4 * 1/4 * 1/4 *1/4 = 1/256

Total = 12/256 + 1/256 = 13/256

Hi Juliette!

How did you know this? Is it a general knowledge?

Yes I was wondering that too!

Hi!

I know this because my highschool taught me about quartiles, i didnâ€™t study it for the IMAT

I find it really hard to figure out what we need to learn in maths for the test even when looking at the syllabus

Ari recommends Barronâ€™s SAT math book, i donâ€™t read it but when i do practice problems and come across a math subject iâ€™m not familiar with i lightly read over the chapter, i think this is the most productive way to go given that we have such a short amount of time left before the exam

Hope this helps!

Oh wait I think I get it! Quartile means 25%. So lower quartile is 25% which is 115. Then the mid quartile is the 25% between 115 and 165. The upper quartile is 165 which is another 25% which gives a total of 75%. So the remaining 25% must be over 165. I think this makes sense to me but correct me if Iâ€™m wrong!

Yes exactly!

Q1 = 0 - 25% of the data

Q2 = the median value and = 0 - 50%

Q3 = 0 - 75% (be carfeful Q3 hold all of these values in it not just the values between 115 and 165)

leaving the last quarter = 75 - 100%

quartiles are just a way to break up large data into different sections

- we usually use quartiles when dealing with large data sets
- we look at itâ€™s difference Q3-Q1 to see its distribution along the median
- we also can choose to only deal with values between Q3 and Q1 and ignore the rest as they are our extreme low and high values that would give us a exaggerated result

Oh i got it! Thank you:)

Oh wow youâ€™re incredible, this is an amazing explanation thank you so much xx