Question

I need help with elementary statistics, solving for the mean, median, etc of a distribution. I know it's simple and I used to know how to do it, but it's been a very long time since I last saw anything math-related and my brain has been dulled.
I scanned the questions. Please help me.
http://uploadir.com/u/67sr58
http://uploadir.com/u/s1g5gp
http://uploadir.com/u/aom94m

Answer 1

for http://uploadir.com/u/67sr58 ; Mean = [(3.5+3.8)/2*16 +(3.9+4.2)/2*24 + (4.3+4.6)/2*30 + (4.7+5.0)/2*20 + (5.1+5.4)/2*10] / (16+24+30+20+10) = 4.386

Answer 2

Median = (50th +51th data) /2 = [(4.3+4.6)/2]*2/2 = 4.45

Answer 3

mode = highest frequency's group ie 30 = [(4.3+4.6)/2 = 4.45

Answer 4

perhaps you can try the other questions yourself

Answer 5

thank you. I have a question for the median, though. why do I have to multiply by two and then divide by 2 again?

Answer 6

(50th +51th data) as they are actually the same, so multipy by 2, then you need to take the average

Answer 7

so divided by 2

Answer 8

in the second question about the upper 50% of the class, is the answer 73?
i took the average of the 70-76 group because 5 of the 15 students don't belong to the 50%.
I don't know how else to approach this...

Answer 9

you're asking for the median?

Answer 10

if you are asking for the median, then it is the value that the 76th datum, ie belong to 500-599, therefore median is (500+599)/2 = 549.5

Answer 11

I mean, the second question in the first image.
But thank you for verifying my answer for the second image.
And if it's not too much a bother, is the mean 585.5?

Answer 12

sorry you're right

Answer 13

for the 2nd question in the 1st image, the passing score = average of the 25th and 26th data, that is (70+76)/2 = 73

Answer 14

callisto is definitely right :)

Answer 15

Thanks thanks.
so, uhhmm, how do I find the deciles, quartiles, and percentiles?

Answer 16

use the total no of students times the percentage you want, you get the nth datum you need, then locate it with the respective group/ value

Answer 17

sorry to bother you again with this
in the second image, is "daily salary" the class boundary? or do i have to subtract/add .5?
i used them as class boundaries and my answer to D3 is 519.8

Answer 18

actually , you need to, i think, not sure for that

Answer 19

sorry but what is D3?

Answer 20

3rd decile, i think

Answer 21

that's 30%?

Answer 22

yes

Answer 23

that's the 45th datum, in the group 500-599 ,therefore D3 = (499.5+599.5)/2 = 549.5