Entering responses in LON-CAPA
Following are some tips for entering answers into the LON-CAPA
homework system.
re: "what is the probability..."
A probability is a number between 0 and 1. In general, it
can be expressed as a decimal, a fraction, or a percentage.
But in LON-CAPA, if you are asked for a probability,
you should respond only with a decimal.
re: "what fraction of..."
re: "what portion of..."
"What portion..." means the same thing as "what fraction...",
and both are asking for a relative frequency.
A relative frequency, like a probability, is a number between 0 and 1.
re: "what percent..."
If you're asked "what percent...", you would generally respond with a
number between 0 and 100 followed by the symbol or word "percent".
In LON-CAPA however, do not enter the percent symbol.
An example
For example, suppose there are 150 students in a class, of
which 85 were women.
If you were asked "What fraction of the class is female?",
generally you could correctly respond "85/150" or "17/30"
or "0.5667" or "56.7%". But in LON-CAPA, you should give
the decimal form "0.5667" only.
If you were asked "What percent of the class is female?" you should
respond with "56.7".
Re: Please adjust significant figures
"Significant figures" (also called "significant digits") is
an idea from the physical sciences that each number has a
precision implied by the digits of its presentation.
Here are some numbers with 3 significant digits, and the
implied precision:
| number | implied precision |
| 105 | +- 1 |
| 31.2 | +- 0.1 |
| 70.0 | +- 0.1 |
| 3.35 | +- 0.01 |
| 1.00 | +- 0.01 |
| 0.002 | +- 0.001 |
Note that both leading and trailing zeroes AFTER the decimal point
are significant.
In the physical sciences, generally, you should not present
a result with greater precision than the data you used to
calculate that result.
Following that rule, then, if you multiply 11.6 * 2.3, which
have 3 and 2 significant figures respectively, you would
calculate 26.68, but then round the answer to 26.7, which
has 3 significant figures, because that is the greatest
precision of the data we were given.
For your purposes here on LON-CAPA, if you get the message
"Please adjust significant figures", then you should either
use more precision or less precision than the answer you gave.
For example, if you enter "3", which has 1 significant digit,
and are asked to adjust your significant figures, that can
only mean you should give MORE precision, so
you would enter "3.0" (2 significant figures)
or "3.00" (3 significant figures).
This topic has its own page:
Entering Units
