guest for dinner

Question

You estimate that 21 1/4% of your guests at dinner will order the special dessert. If 235 guests are expected, how many special desserts should you prepare?

Answer 1

Some questions are so awkwardly worded that you immediately suspect that they are totally math questions poorly disguised as "word (story)" questions to attempt to make them more interesting.  Now, who "estimates" that 21 1/4% of anything will happen??  And, how accurate is the expected number of 235 guests.  How important is it that you have enough, but not too many, desserts?

 

So, let's just word the question, "What is 21 1/4% of 235?"

 

The percent may be expressed as 21 1/4% or as 0.2125 or as 21.25/100.00 or as 85/400 or ... as needed.  Let's use:

                 (0.2125)*235 = 49.9375

 

Now, don't round 49.9375 to a whole person.  Many teachers and tutors will tell you to do that.  While it is true that you must have a whole number of desserts, it is the percent that has already been rounded, not the number of desserts.  The precise number of desserts is 50, so the percent is 21.2766 and it was rounded to 21.25 when the problem was written.

 

This is very important to understand:  The percent was rounded when the problem was written and was not precisely 21 1/4% !!

 

So, prepare 50 desserts.  Or, at least 50 desserts.  Or, roughly 50 special desserts. Or ...

Answer 2

21.25 % or .2125 of 235 = number of special desserts to prepare

 

.2125 x 235 = 49.94. 

 

Round up because you cannot prepare a part of a dessert, and if you round down you will be short

 

49.94 rounded up is 50. 

 

Prepare at least 50 special desserts.