[Blindmath] need help understanding some math concepts

[joe walker]

Hello Cathy,

A truth table is a table containing columns and rows that represents
the truth values for a set of conditions. Given that logic dictates
that a logical state can only consist of true or false values,
according to the law of excluded middle, the numbers 1 and 0 are used
to represent true and false respectively. A truth table organizes all
the possible logical outcomes of a given model in an "easy to look at"
representation in order to quickly make calculations. For a basic
example, let's say that you have decided to go to the store only if
you have money and your car is working.

If you have money, then let's say that (money = 1), otherwise if you
were out of money than (money = 0). If your car is working, than let's
say that (car = 1), if your car wouldn't start for some reason, than
(car = 0). Finally if you have the money and your car starts, than
let's say that (store = 1), otherwise (store = 0). True means that the
conditions have been met or a particular state is active, and false
means that conditions have not been met or a state that is not
currently active. These potential values would be then represented in
a 3 by 3 table hypotheticly. The columns might represent having money
to shop, (money), your car starting, (car), and going to the store,
(store). the rows will represent the possible states, or potential
senarios given the conditions. An example truth table for this
situation might look like something like the following:

money car store
1 1 1
1 0 0

0 1 0

I am not using a table obviously, so instead of interpreting your
screen reader as saying (1 1 1), in the first row, imagine your screen
reader saying (money = 1) (car = 1) and (store = 1). So the first row
says that if you have the money and your car is working, meaning that
both money and car are represented with a number 1, then you will go
to the store, which is why store has a 1 in the first row for truth.
The second row tells us that if you have money, but your car won't
start, you can't go to the store, so store has the number 0
representing a false value. In the third row, you have a working
vehicle, because car has a truth value of 1, but you have no money as
represented by money having a truth value of 0, then store has a truth
value of 0. The essential conclusion from looking at such a truth
table, is that you need both the money and the transportation in order
to go to the store. Truth tables represent everything from electronic
circuits to gramatical structures. As a blind person myself, it took
me a long time to conceptualize this concept, so please let me know if
you have anymore questions.

As far as accessibility in general, I know now that adaptive equipment
exists in order to interpret graphs and mathematical symbols, but the
vast majority of solutions require great financial expendature on your
part, and also are not widely known, so you might never hear about any
of these alternatives from your disability services department at your
university. I hope this helps you in some way, and good luck with
school.

On 1/30/15, Kathy  via Blindmath <blindmath at nfbnet.org> wrote:
> I am taking a General education mathematics course and am strugling with
> certain math calculations.
>
> first of all, I need to try to understand the creation of truth tables in
> logic. Being totally blind I cannot grasp the concept of this table. I need
> someone who can describe this concept verbally instead of visually.
>
> second, I am trying to understand the formula for compound interest: A =
> P(1+RM)N.
>
> The main problem is the book I am using does not read certain symbols, so I
> am having difficulty understanding the operations (multiplication or
> division) that they are using in this formula. the topic we are working on
> is showing how the offer of “no payments until” works out to be misleading.
>
> If anyone out there can help with any of these questions, I would greatly
> appreciate it. I am doing my best to get through college math, but
> accessibility is very poor.
>
> I can be reached by e-mail: kroskos at cox.net or phone: (352) 372-9187.
>
> Kathy
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