can u show me how to solve these 3 math word problems?

[tjaisv]

1) If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together?

2) A student receives his grade report from a local community college, but the GPA is smudged. He took the following classes: a 2 hour credit art, a 3 hour credit history, a 4 hour credit science course, a 3 hour credit mathematics course, and a 1 hour science lab. He received a ?B? in the art class, an ?A? in the history class, a ?C? in the science class, a ?B? in the mathematics class, and an ?A? in the science lab. What was his GPA if the letter grades are based on a 4 point scale? (A=4, B=3, C=2, D=1, F=0)

3) Grace has 16 jellybeans in her pocket. She has 8 red ones, 4 green ones, and 4 blue ones. What is the minimum number of jellybeans she must take out of her pocket to ensure that she has one of each color?

thank u 🙂

 

[nycxandy]

This is so simple. What math class are you taking?

 

[Yossarian]

for the first one, figure out how much of a house each person can do in one hour. other than that, do your own f'n homework 😉

 

[Juice Box]

1) Too Much Work
2) Dont know
3)13 Jellybeans

 

[b0mbrman]

1) RATExxx = 1 paintjob/TIMETOPAINTHOUSExxx ; (RATEjohn + RATEsally) x (X hours) = 1 paintjob; Solve
2) Sum(Grade in class x credits) / total credits
3) Just count jelly beans....

 

[Syringer]

1) 1/4 + 1/6 = 1/x

Where x is how long it takes both of them.

 

[jagec]

amazing. I'm going to pull a random problem out of one of MY textbooks to convince you to do your own homework.

You have been asked to perform a feasibility study on the design of a blood warmer to be used during the transfusion of blood to a patient. This exchanger is to heat blood taken from the bank at 10 C to 37 C at a flow rate of 200 ml/min. The blood passes through a rectangular cross-section tube, 6.4mm by 1.6mm, which is sandwiched between two plates held at a constant temperature of 40 C.
A) Computer the length of the tubing required to achieve the desired outlet conditions at the specified flow rate. Assume the flow is fully developed and the blood has the same properties as water
b) Assess your assumptions and indicate whether your analysis over- or underestimates the necessary length.

...heh, that's actually one of the easy ones 🙂

 

[tjaisv]

Originally posted by: b0mbrman
1) RATExxx = 1 paintjob/TIMETOPAINTHOUSExxx ; (RATEjohn + RATEsally) x (X hours) = 1 paintjob; Solve
2) Sum(Grade in class x credits) / total credits
3) Just count jelly beans....

ty, b0mbrman, lol, i just wasn't able to recognize the formulaic patterns i learned a long time ago in basic algebra to solve these particular word problems...

 

[Juice Box]

for the 3rd one, u assume the worst situation, you first full all 8 red oens, then all 4 blue ones THEN 1 green one

8+4+1=13 🙂

 

[nycxandy]

Originally posted by: jagec
amazing. I'm going to pull a random problem out of one of MY textbooks to convince you to do your own homework.

You have been asked to perform a feasibility study on the design of a blood warmer to be used during the transfusion of blood to a patient. This exchanger is to heat blood taken from the bank at 10 C to 37 C at a flow rate of 200 ml/min. The blood passes through a rectangular cross-section tube, 6.4mm by 1.6mm, which is sandwiched between two plates held at a constant temperature of 40 C.
A) Computer the length of the tubing required to achieve the desired outlet conditions at the specified flow rate. Assume the flow is fully developed and the blood has the same properties as water
b) Assess your assumptions and indicate whether your analysis over- or underestimates the necessary length.

...heh, that's actually one of the easy ones 🙂

What textbook?

 

[Gurck]

y r u wan 2 no??/?//questionmarkquestionmark

 

[tjaisv]

now that i've read the third one over and over again i finally get it: if you're supposed to have 1 of each color, then u'd have to pull out 13 of them...finally makes sense ok

i'm still trying to get the sense of the other two tho

 

[Yossarian]

Originally posted by: jagec
amazing. I'm going to pull a random problem out of one of MY textbooks to convince you to do your own homework.

You have been asked to perform a feasibility study on the design of a blood warmer to be used during the transfusion of blood to a patient. This exchanger is to heat blood taken from the bank at 10 C to 37 C at a flow rate of 200 ml/min. The blood passes through a rectangular cross-section tube, 6.4mm by 1.6mm, which is sandwiched between two plates held at a constant temperature of 40 C.
A) Computer the length of the tubing required to achieve the desired outlet conditions at the specified flow rate. Assume the flow is fully developed and the blood has the same properties as water
b) Assess your assumptions and indicate whether your analysis over- or underestimates the necessary length.

...heh, that's actually one of the easy ones 🙂

hey I used to know how to do that! heat transfer was so easy, it's totally empirical. you just gotta find the right formula and plug stuff in.

 

[b0mbrman]

Originally posted by: tjaisv
now that i've read the third one over and over again i finally get it: if you're supposed to have 1 of each color, then u'd have to pull out 13 of them...finally makes sense ok

i'm still trying to get the sense of the other two tho

Basically, remember that Rate x Time = Work done

For 2, you're really just taking a weighted average

 

[tjaisv]

Originally posted by: b0mbrman

Originally posted by: tjaisv
now that i've read the third one over and over again i finally get it: if you're supposed to have 1 of each color, then u'd have to pull out 13 of them...finally makes sense ok

i'm still trying to get the sense of the other two tho

Basically, remember that Rate x Time = Work done

For 2, you're really just taking a weighted average

 

[tjaisv]

Originally posted by: b0mbrman

Originally posted by: tjaisv
now that i've read the third one over and over again i finally get it: if you're supposed to have 1 of each color, then u'd have to pull out 13 of them...finally makes sense ok

i'm still trying to get the sense of the other two tho

Basically, remember that Rate x Time = Work done

For 2, you're really just taking a weighted average

ok got the 1st one now...i followed the advice of another poster and figured out how much of a house each person can do in an hour, and then realized the equation would be (1/4 + 1/6)x = 1, which another poster mentioned too 🙂 tx

 

[dethman]

is this for real?