Homework Help v1.3

[batman555]

^ Here's my solution. It's easier to write it out than to try to type it out.

[Ice(v)an]

Sociology sees itself as the most general of all the social sciences and the one that seeks to integrate the findings of all the others. As a consequence, other social scientists tend to see sociologists as the jack of all trades, but the master of none of them.


True or False?

[Konfucius]

Ztool, that is the easiest question ever..

[pkzild]

The physical half life of 109 Cd is 460 days. A new source of activity 10 GBq(giga becquerel) is purchased. The source can be used until its activity decreases to 2.0 GBq. How long does it take for the source activity to fall from 10GBq to 2.0GBq?

[lima.beans]

from research I find that the equation t = -(T1/2/0.693) * ln(N/No)

where as
T1/2 is the half-life : 460 days in your case
N is the final activity : 2GBq
No is the initial activity : 10GBq

plug in the numbers and you should get something like 1052 days.

[pkzild]

hmm close but i got 1093 days on my first attempt at calculation.. finally figured it out i thought

this was my procedure:

A (activity) = λ (being decay constant)*N


λ= ln(2)/t(half life)
= ln(2)/460days
= 1.5 x 10^-3 d^-1

N= A/λ = 2.0GBq/1.5 x 10^-3
= 1.3 x 10^3
No = Ao/λ = 10GBq/1.5 x 10^-3
= 6.7 x 10^3

therefore using the generic half life decay formula

N = No e^-λt

1.5x10^-3*t = ln (1.3x10^3 / 6.7x10^3)
t = Approx. 1093


Please correct if this is wrong

[lima.beans]

I used the wrong numbers on the first attempt of mine. I redid it and wound up with 1068.3

[batman555]

Hmm...my answer came out to be different.

half-life = ln(2)/k
==> k = ln(2)/half-life
==> k = ln(2)/460
==> .0015 days^-1

For a 1st order decay (from what I did in class):
ln(A/Ao) = -kt

where A = final concentration and Ao = initial concentration

.: ln(2/10) = -.0015t
.: t = 1073 days

Dunno...I might be wrong...

[RagingVortex]

you and lima both have the right answer, lima's is more accurate because he plugged in ln2/halflife for k and didn't solve for it earlier

[pkzild]

Yeah I should've been rearraging my equation around first before subbing numbers in later.. I got 1068.3 as well lima thanks a lot and thanks batman for trying also

[pkzild]

Sorry for double post, but it's a new assignment so...
I need major help in MS Excel, anyone who knows how to walk me through in this I will appreciate very much maybe even I'll buy you something via Paypal (damn im desperate)
Now I'm not saying you should do it all for me, I need some help in using these functions correctly... Just msg me if you know and are very familiar with those functions listed below in bold


The Problem:

Body Mass Index (BMI) is a number that shows body weight adjusted for height.

BMI can be calculated by the following formula:

BMI = 10000 x Mass(kg)/Height^2 (cm)


Based on the result, the following Categories can be used:

Range Category Value
BMI < 18.5 : underweight
18.5 <= BMI < 25 : normal
25 <= BMI < 30 : overweight
BMI >= 30 : Obese


Your task will be to make a worksheet that can calculate BMI and also
some other things.

Normally, real data is collected (e.g. gender, first and last names, height
and weight), the calculations are done and statistics are gathered as well.

Since we don't have any data, random numbers will be used.

Randomly generate the following:

Gender : M or F
First name : Find at least 50 male and 50 female names (check the Web).
Depending on what gender was generated, randomly select an
appropriate male or female name.
Last name : Find at least 75 lastnames (check the web). Randomly pick from
the names.
height (cm): Randomly generate a value in the range [A..B]. Where A and B
are reasonable values with respect to height.
weight (kg): Randomly generate a value in the range [C..D]. Where C and D
are reasonable values with respect to weight.

Once these values get generated, the BMI and Category values can be calculated.
Use a function to round the BMI value to one decimal place.
Create 60-120 rows of data and calculations.

Once all the rows and calculations are done, calculate the frequency of the
Category Values. Create a graph that will display the frequency results.
Pick an appropriate graph type and also label the graph.

Include on the worksheet, a title, your name and ID, course,
and tutorial. Also add appropriate labels for the data and calculations.
Use some of the tips and notes discussed in class and in the lecture slides.

Notes:

- Pressing the F9 key in Excel will make RAND() regenerate new values.
Your graph and calculation should automatically adjust.

- The following EXCEL functions may be useful (all may not be needed):
RAND(), IF(), INDEX(), VLOOKUP(), HLOOKUP(), COUNTIF(), ROUND(), SUM(),
COUNTA(), COUNT(), TRUNC()



What I'm stuck on basically is how to randomly generate F/L names, gender according to names

I've done the rest already (height, weight, BMI, Category)

[Denny Crane]

BMI is
weight (kg)/height^2 (metres)

[pkzild]

Originally Posted by kazman3

BMI is
weight (kg)/height^2 (metres)

yo nigga dont fret over details this is the exact instruction given on the assignment we use whatevers given whether wrong or right

btw I dont need help nemore... figured it all out today =D

[Banana_Alchemist]

=O science design challenge i dunno how to make any of the 3 chocies...

1) A pneumatically or hyrdaulically operated safety hinge:
Design and build a model of a door that opens or closes using pneumatics or hydraulics.

2)A Boat Navigation lock:
Design and build a model of a navigation lock model that allows boats to travel between waterways of different levels

3)A fish-tank Cleaner
Design and build a fish-tank cleaning device that will rasie or lower itself in water

[sadated_peon]

Originally Posted by Banana_Alchemist

=O science design challenge i dunno how to make any of the 3 chocies...

1) A pneumatically or hyrdaulically operated safety hinge:
Design and build a model of a door that opens or closes using pneumatics or hydraulics.

2)A Boat Navigation lock:
Design and build a model of a navigation lock model that allows boats to travel between waterways of different levels

3)A fish-tank Cleaner
Design and build a fish-tank cleaning device that will rasie or lower itself in water

I would choose the hydraulic door, get a small motor and lots of platic tubing and you have all the tech materials you will need.

[Banana_Alchemist]

I don't really think i can get a small motor...
and since i'm in grade 8 i don't really think our teacher really wants something thats hard to make for our design challenge.

thanks anyways

[RagingVortex]

Originally Posted by Banana_Alchemist

=O science design challenge i dunno how to make any of the 3 chocies...

1) A pneumatically or hyrdaulically operated safety hinge:
Design and build a model of a door that opens or closes using pneumatics or hydraulics.

2)A Boat Navigation lock:
Design and build a model of a navigation lock model that allows boats to travel between waterways of different levels

3)A fish-tank Cleaner
Design and build a fish-tank cleaning device that will rasie or lower itself in water

I'd definitely do #2. Basically you need 2 big gates in the water, such that you have one water level on the left, and the different level on the right. The gate on the left opens so the boat goes into the middle section. Water is added/removed through a small trapdoor on the right gate. Then when the water level is the same as the right side, the right gate opens, and voila! There's another trapdoor on the left gate for travel in the opposite direction. This system is called a lock:
http://en.wikipedia.org/wiki/Canal_lock

[Jeaxz]

Does anyone have an idea on miltary applications for the army???? I need some info on the military apllications for the land units. thanks

[Banana_Alchemist]

Originally Posted by RagingVortex

I'd definitely do #2. Basically you need 2 big gates in the water, such that you have one water level on the left, and the different level on the right. The gate on the left opens so the boat goes into the middle section. Water is added/removed through a small trapdoor on the right gate. Then when the water level is the same as the right side, the right gate opens, and voila! There's another trapdoor on the left gate for travel in the opposite direction. This system is called a lock:
http://en.wikipedia.org/wiki/Canal_lock

Thanks, it seems easy ^^, the only thing now is to get the materials O.o

[canza]

Every rule has its exceptions. One particularly interesting exception to a rule is......

can some one fill the blank with some examples?