SOLUTION: The repair department of the bicycle shop repairs three things: flat tires, bent handle bars and ripped seats. Today in the repair department, 25% of the bikes had flat tires only

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Question 1100944: The repair department of the bicycle shop repairs three things: flat tires, bent handle bars and
ripped seats. Today in the repair department, 25% of the bikes had flat tires only, 5% had bent
handlebars only, and 10% had ripped seats only. Just 1/12th of the bikes had all three repairs to
do: flat tires, bent handlebars and ripped seats. No bikes were completely fixed and there are a
total of 101 repairs to be made. How many bikes are in the repair department? How many bikes
need two repairs? If less than half of all the bikes have a ripped seat, what is the range of bikes
that need both the tires and handlebars repaired without needing to fix the seat?

Found 2 solutions by KMST, richwmiller:
Answer by KMST(5328)   (Show Source): You can put this solution on YOUR website!
ONE APPROACH:
= number of bikes in the shop waiting to be repaired.
Of those,
25% have flat tires only,
5% have bent handlebars only, and
10% have ripped seats only.
That adds up to 25%+5%+10%=40% .
So, the number of bikes needing only 1 repair is
.
The number of bikes needing 3 repairs is .
The rest of the bikes is the fraction of all bikes that need exactly 2 repairs.
As a fraction of all the bikes, that is
.
As a number of bikes, it is
.
Counting the number of repairs needed, we have
repairs for the bikes that need only 1 repair,
repairs for the bikes that need exactly 2 repairs,
and
repairs for the bikes that need 3 repairs.
The number of repairs adds up to






There are bikes in the repair department.

Of those bikes,
need exactly two repairs,
, or bikes, need all 3 repairs including their ripped seats,
25% , or bikes, only need flat tires fixed,
5% , or bikes, only need bent handlebars fixed, and
10%, or bikes only need their ripped seats fixed.
In pictures, we could represent is as
.
The last question asks for the range of values for value of ,
The number of "bikes
that need both the tires and handlebars repaired without needing to fix the seat".

From the picture,
if , is the greatest possible ;
If , is the least possible .

Without a picture:
If is the total number of ripped seat repairs,
we do not know exactly, but
it includes at least the that need only the seat repaired,
and the that need all 3 repairs, so
or .
If less than half the bikes have a ripped seat
(meaning or less bikes),
we also know that , so
.

If we exclude
those bikes with ripped seats,
the bikes that only need flat tires fixed,
and the bikes that only need bent handlebars fixed,
we are excluding ,
what is left is the group of bikes that needs
"both the tires and handlebars repaired without needing to fix the seat."
That number is .
As ,

.
There are at least and at most bikes that need
"both the tires and handlebars repaired without needing to fix the seat."
The range can be expressed as [13,31], or as

Answer by richwmiller(17219)   (Show Source): You can put this solution on YOUR website!
Nicely done!!
There seems to be a typing error.


should probably be


Warning: I am still sick in bed. Double check my work.

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