Questions
1. An ant is climbing up a wall. How long will it
take the ant to reach a 3m wall if the ant climbs up 3 cm and falls
back 1 cm every second.
2. In a multiple choice question test, there are 4 choices for
each question and there are 50 questions. If a student scores 2
marks for a correct answer and 1 mark will be deducted for a wrong
answer. How many questions do the student answer correctly if this
student scores a total of 67 marks ?
3. Mr Loo had to deliver 800 hampers in May. He received $4 for
every hamper that was delivered successfully and $7 would be
deducted from his salary for every hamper that was damaged. If his
salary in May was $2,430 , how many hampers did Mr Loo deliver
successfully?
4. There are 100 cats and hens and there are 344 legs
altogether. How many cats are there ?
Solutions
1. For every one second, the ant climbs 3 cm and falls 1 cm,
this means that the ant climbs 2 cm every second. So, to climb a
wall of 3m, the ant will take 300cm / 2 cm = 150 seconds = 2
minutes and 30 seconds.
2. Assume the student get all 50 question correct ie 50 x 2 =
100 marks.
For every one wrong answer, 2 + 1 = 3 marks will be
deducted.
100 - 67 = 33 marks less
33/3 = 11 wrong answers
So, 39 correct answers and 11 wrong answers ie the student will
get a total mark of 39 x 2 - 11 x 1 = 67 marks.
3. Assume that Mr Loo delivers 800 successfully ie 800 x $4 =
$3200
For every one damaged, $4 + $7 = $11 will be deducted.
$3200 - $2430 = $770 less
$770 / $11 = 70 hampers are damaged.
4. Assume that all animals are cats ie there will be 100 x 4
legs = 400 legs
Now, for every 2 legs less means 1 hen.
400 - 344 = 56 legs less
So, 56/2 = 28 hens
Hence, there are 100 - 28 = 72 cats
Check : 72 x 4 + 28 x 2 = 344 legs.