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well a proportion compares part of a quanity to the whole quanity called the base using a percentprobabiltyis the cahnce of an event happening for example like getting a puppy that is a simple event
There is no simple answer. There are two main factors need to be taken into account. Consider the simple case of a dichotomous or binary variable.One consideration is the consequences of getting the proportion wrong. If you are estimating the proportion of males (and females) going to a cinema so as to design the correct number of toilets, a 5% risk of getting it wrong may be acceptable. You may have some disgruntled customers and, in any case, it may be possible to rebuild and re-designate some toilets. If, instead, you are estimating the proportion of people who have a serious adverse reaction to some medication, a 5% error rate is catastrophic! Not just for the patient but for the pharmaceutical company as well.Such risk assessment will determine the confidence level that you require from the estimate. Suppose now that for the study under consideration, a 5% risk of getting it wrong is acceptable. That is, you want to be 95% confident that the true (but unknown proportion) is within 1.96 standard errors of your estimate.If the true proportion is around 50%, then a sample size of just under 100 will suffice. However, if you are trying to estimate the proportion of a rare characteristic - whose true incidence in the population is 0.5% - then for the same degree of confidence in the estimate you will need a sample of over 19,000.
A simple tool to remember is: IS over OF equals percent over 100.If we put this into a proportion, we get:IS/OF = percent/100.Just put all percent problems into this format, and solve the proportion.Example: 12.5 IS what percent OF 75?Or,12.5 IS | what percent | OF 75?Just put these numbers into the proportion: (We will use x for the percent, as that is the unknown we are solving for)12.5/75 = x/100.Then solve by cross multiplying:75x = 1250.Then divide by 75:x = 1250/75,x = 16 2/3 %
I assume that "public" simply means population. The simple answer is that Greater London has a population of 8.174 million compared with England's population of 53.012 million, representing 15.4%. However, less than half of London's population (44.9%) is "White British". Removing the Welsh, Irish and Scots people, the English proportion of London's population will be considerably smaller. On the other hand a significant proportion of England's population is not English either.
it depends what textbook you have. basically it's ratio, proportion, division of fractions, the pythagorean theorem, surface area, volume, compound and simple interest, markup and selling prices, formulas, simplifying exponential expressions, and so on. there's a lot more but this is some from the Foundations for Algebra series. Hope this helps!