Question

1. In a class of 24, 3 students were absent, What fraction of class is present

2. Karen taped a television show that lasted 1h 30mins. On the same tape she recorded another 2 shows that were 5/6h each. What time was still left on the 4h tape.

3. Steve ordered 12 lengths of timber, each 6m long. He cut 6 lengths into 1 1/2m pieces and the other 6 lengths into 3/4 pieces A. How many pieces together is this? B. Was there any waste?

Answer 1

Problem 1

Answer: 7/8 of the class is present

Reason:

24 people total with 3 absent. So 24-3 = 21 are present

21/24 = (7*3)/(8*3) = 7/8

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Problem 2

Answer: 50 minutes left on the tape.

Work Shown:

1 hour = 60 min

(5/6)*(1 hour) = (5/6)*(60 min)

5/6 of an hour = 50 min

1 hr + 30 min = 60 min + 30 min = 90 min

The first show is 90 minutes. Add on two more shows that are 50 min each to get 90+50+50 = 190 minutes used up

4 hours = 4*60 = 240 min

240 - 190 = 50 min

There are 50 minutes left on the tape.

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Problem 3

Answer: 72 pieces; not enough info to calculate the waste

Step-by-step explanation:

1 1/2 = 1 + 1/2 = 1 + 0.5 = 1.5

6/(1.5) = 4

Each 6 meter board is cut into 4 equal pieces each 1.5 meters long

There are 6 boards this applies to which means so far that's 6*4 = 24 pieces

Now to the other 6 boards.

3/4 = 0.75

6/(0.75) = 8

Each of the other 6 boards are cut into 8 equal pieces of 0.75 meters each

That's another 6*8 = 48 pieces

In total there are 24+48 = 72 pieces

When cutting into wood, there always is a small sliver that is discarded. While small, these slivers do add up. So yes there is some waste. Unfortunately, we don't have enough info to calculate. We would need to know the width of the saw blade.