Q&A - PSLE Math
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MathIzzzFun:
After long thinking, I think I got it. But still blur how can we just take that 3AB = 3X64km. Coz I still thinking that AB = 64km + 52km + unknown distance. Let me sink in the idea ... :thankyou: MathIzzzFun.
HiCDE:
need explanation on math qn, from MO advanced by Terry Chew. Its from chapter 8, qn no. 7.
car A departed from town A and travelled toward town B. At the same time, car B started its journey in the direction of town A from town B. the two cars passed each other 64km away from town B and carried on with their journey. They made U turn upon arriving at the destination so as to return to their town. they passed each other again, this time 52 km away from town A. find the distance between the two point where they passed each other.
key answer:
analysis: the total distance of covered by the two cars is 3 times the distance between town A and town B.
distance covered by car B = 64 x 3
= 192 km :? **this part really blur**
distance between town A and B = 192-52
= 140km
140 - 64 - 52 = 24km
the distance between the two points where they passed each other was 24km.
anyone can explain the highlighted blue part? the rest is understood. thanks...
when the two cars first met (say at X), Car B travelled 64km; total distance covered by both cars = distance between A & B.
when the two cars met again the second time (say at Y), the total distance covered by both cars = 3 x distance A & B
--> at first meeting point, distance covered by both cars = AX (car A)+ BX (Car B) = AB
--> when the cars reach town A & B, total distance travelled by both cars = XA (car B) + XB (car A) = AB
--> when the cars turn round meet at Y, distance travelled by both cars = AY (car B) + BY (car A) = AB
so, total distance travelled when the cars meet a second time = 3 x AB
When total distance travelled is AB, car B travelled 64 km
When total distance travelled is 3x AB, car B would have travelled 3 x 64 km = 192 km
cheers. -
CDE:
Hi
After long thinking, I think I got it. But still blur how can we just take that 3AB = 3X64km. Coz I still thinking that AB = 64km + 52km + unknown distance. Let me sink in the idea ... :thankyou: MathIzzzFun.MathIzzzFun:
need explanation on math qn, from MO advanced by Terry Chew. Its from chapter 8, qn no. 7.
car A departed from town A and travelled toward town B. At the same time, car B started its journey in the direction of town A from town B. the two cars passed each other 64km away from town B and carried on with their journey. They made U turn upon arriving at the destination so as to return to their town. they passed each other again, this time 52 km away from town A. find the distance between the two point where they passed each other.
key answer:
analysis: the total distance of covered by the two cars is 3 times the distance between town A and town B.
distance covered by car B = 64 x 3
= 192 km :? **this part really blur**
distance between town A and B = 192-52
= 140km
140 - 64 - 52 = 24km
the distance between the two points where they passed each other was 24km.
anyone can explain the highlighted blue part? the rest is understood. thanks...
Hi
when the two cars first met (say at X), Car B travelled 64km; total distance covered by both cars = distance between A & B.
when the two cars met again the second time (say at Y), the total distance covered by both cars = 3 x distance A & B
--> at first meeting point, distance covered by both cars = AX (car A)+ BX (Car B) = AB
--> when the cars reach town A & B, total distance travelled by both cars = XA (car B) + XB (car A) = AB
--> when the cars turn round meet at Y, distance travelled by both cars = AY (car B) + BY (car A) = AB
so, total distance travelled when the cars meet a second time = 3 x AB
When total distance travelled is AB, car B travelled 64 km
When total distance travelled is 3x AB, car B would have travelled 3 x 64 km = 192 km
cheers.
it is in ratio....
total distance : distance travelled by car B : distance travelled by car A
= AB : 64 : distance travelled by car A from A to X
= 3x AB : 3 x64 : 3 x distance travelled by car A from A to X
cheers. -
CDE:
Hi
After long thinking, I think I got it. But still blur how can we just take that 3AB = 3X64km. Coz I still thinking that AB = 64km + 52km + unknown distance.
Hope this helps.
Best wishes![](\"http://farm9.staticflickr.com/8003/7619822038_9f3f89b73a_z.jpg\")
http://farm9.staticflickr.com/8003/7619822038_9f3f89b73a_z.jpg\">
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Boa Di had 30 dollar, 20 dollar and 10 dollar tickets for a school concert in the ratio 1:5:4. The total value of the concert tickets was $3060.
How many 10 dollar tickets had he? -
dora miscq:
Hi,Boa Di had 30 dollar, 20 dollar and 10 dollar tickets for a school concert in the ratio 1:5:4. The total value of the concert tickets was $3060.
How many 10 dollar tickets had he?
You can solve this Question by Quantity x Value.
$30x1=30
$20x5=100
$10x4=40
total-100+40+30=170
3060/170=18
He had 18 sets of 1:5:4 .
From here,you can solve the question.
cheers -
Anyone help?
A group of girls shared some sweets among themselves. They tried taking 11 sweets each, but found that the last girl had only 6 sweets. When each girl took 8 sweets, there were 25 sweets left over. How many sweets were there altogether? -
Michaelia0816:
Hi girlAnyone help?
A group of girls shared some sweets among themselves. They tried taking 11 sweets each, but found that the last girl had only 6 sweets. When each girl took 8 sweets, there were 25 sweets left over. How many sweets were there altogether?
This is a tweaked version of the familiar “excess and shortage” type of questions.
Restate the question in another way and I am sure you’ll find it familiar.
A group of girls shared some sweets among themselves. If each of them were to take 11 sweets, they would be short of 5 sweets. If each girl were to take 8 sweets, they would have 25 sweets left.How many sweets were there altogether?
25 + 5 ------- 30
11 – 8 ------ 3
Number of girls ----- 30/3 ------- 10
Number of sweets ------- (10*8) + 25 ------ 105
Best wishes -
Thx, Tianzhu, now I understood, that why I Cannot get it correct!
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Need help for these 2 questions :
1) The average height of a group of children was 139.4cm. When the height of these children was measured and recorded, one child’s height was wrongly recorded as 192cm when it should have been 129 cm. As a result, the average height of this group of children was calculated as 142.4 cm. How many children were there in the group?
2) 3 friends bought the same number of fruits each. Alan bought 5 oranges and some apples and paid $7.80. BOb bought 11 oranges and some apples and paid $9. How much did Chris pay if he bought only apples ?
Thank u ! -
2DMommy:
HiNeed help for these 2 questions :
1) The average height of a group of children was 139.4cm. When the height of these children was measured and recorded, one child's height was wrongly recorded as 192cm when it should have been 129 cm. As a result, the average height of this group of children was calculated as 142.4 cm. How many children were there in the group?
This question has been discussed before.
Best wishes
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