P6 Maths
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Q1 Tank A and Tank B were filled with water ti the brim. The water was drained out of the tanks at the same time. Water in Tank A would be completely drained out in 5 minutes while the water in Tank B would take 8 minutes to drain out completely. After 2 minutes, the height of the remaining water in the two tanks was the same. Find the ratio of the height of Tank A to the height of Tank B.
Q2 David has stack of rectangular cards measuring 8 cm by 6 cm. How many cards does he need to put together to form the smallest possible square ?
Q3 Some boys and 20 girls collected an average of 26 stamps. The girls collected an average of 30 stamps. If each boy collected an average of 8 stamps less than each girl, how many were there altogether ?
Q4 21 scouts wanted to cross a river, which was 3 km wide. They managed to find a small abandoned boat. The boat could carry only 3 persons at a time. What was the distance the boat had to travel to bring all the scouts across the river ?
Q5 A snail crawled up a tree at a rate of 2 cm per minute. However for every 2 cm it crawled up, it would take a rest for another minute. During the rest, it would slip down 1 cm because of gravity acting on its heavy shell.
(a) What was the distance the snail from the ground at the end of10th minute? (b) If the tree was 2.2 m tall,what was the time taken by the snail to crawl up the tree?
Q6 The ratio of the number of pupils in Class 6A to the number of pupils in Class 6B was 4: 3 at first. 1/4 of the pupils in Class 6A and 5/6 of the pupils in Class 6B were girls.After reshuffling some of the pupils between the two classes, the number of boys in each class became the same number of girls. If a total of 20 pupils was affected, how many pupils were there in Class 6B at first ?
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Q2: Just find the highest common factor, which happens to be 24. That will give you your required number of cards of 12.
Q4: The boat needs to travel 6km to send 2 people across at the start, except for the last where it needs to travel 3km to send 3 people across. Hence, should be 57km?
Q5a) 5 cm (b) It needs 2 mins to travel 1 cm each time, except for the last where it needs 1 min to travel 2 cm. Same as question 4 =P
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Originally posted by Chocolate Cake:
Q1 Tank A and Tank B were filled with water ti the brim. The water was drained out of the tanks at the same time. Water in Tank A would be completely drained out in 5 minutes while the water in Tank B would take 8 minutes to drain out completely. After 2 minutes, the height of the remaining water in the two tanks was the same. Find the ratio of the height of Tank A to the height of Tank B.
Q2 David has stack of rectangular cards measuring 8 cm by 6 cm. How many cards does he need to put together to form the smallest possible square ?
Q3 Some boys and 20 girls collected an average of 26 stamps. The girls collected an average of 30 stamps. If each boy collected an average of 8 stamps less than each girl, how many were there altogether ?
Q4 21 scouts wanted to cross a river, which was 3 km wide. They managed to find a small abandoned boat. The boat could carry only 3 persons at a time. What was the distance the boat had to travel to bring all the scouts across the river ?
Q5 A snail crawled up a tree at a rate of 2 cm per minute. However for every 2 cm it crawled up, it would take a rest for another minute. During the rest, it would slip down 1 cm because of gravity acting on its heavy shell.
(a) What was the distance the snail from the ground at the end of10th minute? (b) If the tree was 2.2 m tall,what was the time taken by the snail to crawl up the tree?
Q6 The ratio of the number of pupils in Class 6A to the number of pupils in Class 6B was 4: 3 at first. 1/4 of the pupils in Class 6A and 5/6 of the pupils in Class 6B were girls.After reshuffling some of the pupils between the two classes, the number of boys in each class became the same number of girls. If a total of 20 pupils was affected, how many pupils were there in Class 6B at first ?
Since ThunderFBolt has kindly answered Questions 2, 4 and 5, I will only touch on Questions 1, 3 and 6.
Q1.
Tank A will be drain in 5 mins, while Tank B will be drain in 8 mins.
After 2 mins,
2/5 of Tank A will be drained and 2/8 of Tank B will be drained.
= > 3/5 of Tank A and 6/8 of Tank B will be left.
= > 3/5 of Tank A = 3/4 of Tank B
Thus, ratio of Tank A's height to Tank B's height = 5 : 4
Q3.
Some very basic algebra involved here.
Let the numbers of boys be x.
There are 20 girls and they collected an average of 30 stamps each.
Total stamps that girls collected = 20 X 30 = 600 stamps
Each boy collected an average of 8 stamps less than each girl.
= > Each boy collected an average of 22 stamps each
Total stamps that boys collected = 22x stamps
= >
[ ( Stamps boys collected ) + ( Stamps girls collected ) ] / Total children
= Total average stamps collected per child
( 22x + 600 ) / ( 20 + x ) = 26
22x + 600 = 520 + 26x
4x = 80
x = 20
= > number of boys = x = 20 boys
Q6.
Number of students in class A to B = 4 : 3 = 8 units : 6 units
Let G be girls and B be boys
Class A l_G_l_G_l_B_l_B_l_B_l_B_l_B_l_B_l
Class B l_G_l_G_l_G_l_G_l_G_l_B_l
The bolded parts are the students who are reshuffled.
Hence, 4 units of students are affected.
= > 4 units = 20 students
= > 1 unit = 5 students
= > Total students in class B = 6 units = 6 X 5 = 30 students.
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Originally posted by ThunderFbolt:
Q2: Just find the highest common factor, which happens to be 24. That will give you your required number of cards of 12.
Q4: The boat needs to travel 6km to send 2 people across at the start, except for the last where it needs to travel 3km to send 3 people across. Hence, should be 57km?
Q5a) 5 cm (b) It needs 2 mins to travel 1 cm each time, except for the last where it needs 1 min to travel 2 cm. Same as question 4 =P
For Q4, it is 57km indeed.
For Q5b), the answer is ( 218 X 2 ) mins + 1 min = 437 mins
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Originally posted by Forbiddensinner:
For Q4, it is 57km indeed.
For Q5b), the answer is ( 218 X 2 ) mins + 1 min = 437 mins
haha, thanks for the check. i was doing this at the top of my head and just lazy to think. =P
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You may want to refer to the following Blog for primary school Maths:
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Originally posted by Tang1:
You may want to refer to the following Blog for primary school Maths:
Excellent website for Primary School Maths.
Thanks for sharing the website.