Question #47bec

2 Answers
Mar 31, 2017

#35.7%#

Explanation:

#0.25/70=0.357...#

#0.357xx100=35.7%#

Mar 31, 2017

#35 5/7%# Exactly

If you use decimals you do not have a precise answer

#~~35.71%# to 2 decimal places #larr# approximately

Explanation:

#color(blue)("Very important facts about percentages")#

Percent is just another fraction. The special thing about percent is that the bottom number (denominator) is fixed at 100.

The symbol % is like a unit of measurement but one where it is worth #1/100#

So as an example: 20%#->20xx%->20xx1/100=20/100#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
#color(blue)("Answering the question")#

Let the unknown value be #x# then we have:

#25/70=x/100#

To 'get' #x# on its own we need to 'get rid' of the 100 in #x/100#. We do this by changing into 1 because #1xx x" gives just "x#

Multiply both sides by 100

#color(green)(25/70color(red)(xx100)" "=" "x/100color(red)(xx100))#

#color(green)(5/14color(red)(xx100) " "=" "x xx (color(red)(100))/100)#

but #100/100# is the same as 1 giving:

#x=35 5/7#

So we have:#" "(35 5/7)/100" "=" "35 5/7xx1/100" "=" "35 5/7%#