#3 3/4# is bigger than #1 19/21#. How many times bigger?

2 Answers
Oct 27, 2016

#3 3/4# is roughly 2 times bigger than #1 19/21#

Explanation:

So we have to fractions,

#3 3/4# and #1 19/21#

which are equivalent to,

#15/4# and #40/21#

to find how many times bigger #3 3/4# is we equate the fractions and multiply one side by a variable.

#15/4=x*40/21#

#15*21=x*40*4#

#315=160x#

#x=63/32#

#x~~ 2#

So #3 3/4# is roughly 2 times bigger than #1 19/21#

Oct 27, 2016

This is a division problem: you're trying to find the ratio between the two numbers.

Explanation:

#x=(3 3/4)div(1 19/21)#

We first convert from mixed fractions:
#(3*4/4+3/4)div(1*21/21+19/21)=15/4div40/21#

Division by a fraction equals multiplying by its inverse:

#15/4xx21/40=(15*21)/(4*40)#

We can only cancel out a #5# from both #15# and #40#:

#(3*cancel5*21)/(4*cancel5*8)=63/32=1 31/32#

So the higher number is almost (but not quite) twice as big as the smaller, or #31//32#th bigger.