Quick
Answer:
Nine more
shows. |
|
Complete
Solution:
You can consider
this problem in terms of minutes or in units of half-hour
shows. Using only the SP setting, the tape
can record 120 minutes of shows. If one 30 minute show
has already been recorded, 1/4 of the tape has been used.
Type
of Setting |
Minutes
Used |
Total
Minutes on Tape |
Portion
of Tape Used |
SP |
30 |
120 |
30/120
or 1/4 |
EP |
(1/4)
×
360, or 90 |
360 |
90/360
or 1/4 |
With 1/4 of the tape filled, 90 minutes
of EP has been used, so that there are 360-90 or 270 minutes
left. At 30 minutes per show, nine additional shows can
be taped.
If you are using
half-hour units, there are four half-hour shows
on SP in two hours. One half-hour show used 1/4 of the
tape. Three-fourths of the tape is left. With EP, you
can do 12 half-hour shows, and then you have enough tape
for 3/4 ×
12, or 9 shows remaining.
Yet another way
to consider this problem is to use proportions
as follows:
Because 3 ×
120 = 360 and 3 ×
30 = 90, there are 90 minutes used on the EP setting,
so that there are 360 - 90, or 270 minutes available which
allows for 9 thirty-minute shows
on EP.
Similarly 30 ×
360 = 120 ×
(x number of minutes), so the number of minutes
is 90. |
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