## Tuesday, October 20, 2009

### PSLE Maths Question with Workings

The below are some questions with workings asked in this year's 2009 PSLE Maths paper.

Question 1
The above figure is a square. The angle question answer above is 150 degrees. Because the bottom triangle is equilateral triangle. (draw a circular curve through all 3 lines and they become the radii of the incomplete circle otherwise known as the arc)
360 - 60 = 300 degree
300 degree / 4 = 75 degree
75 degree x 2 = 150 degree

Question 2

6 friends decided to rent computers from 2pm to 4.30pm. While 4 of them were playing, the other two would watch. If the cycle continues, and each of them played for equal number of minutes, how many minutes will each person get to play? Ans: 100 minutes

Question 3

Mei and Lin were in a bicycle race. Mei was travelling at a constant speed of 20km/hr and they both did not change their speed. When Lin completed half the race, Mei was 3.5km ahead. Mei completed the race at 10.45am. What time did Lin complete the race? Ans: 11.06am

Question 4

Sally baked some cookies to sell. 3/4 of them were chocolate cookies and the remaining were almond cookies. After she sold 5/6 of chocolate cookies and 210 almond cookies, she had 1/5 of the cookies left. How many cookies did she sell? Ans: 960

Question 5

Jim bought some chocolates and gave half of it to Ken. Ken bought some sweets and gave half of it to Jim. Jim ate 12 sweets and Ken ate 18 chocolates. The ratio of Jim's sweets to chocolates became 1 : 7 and the ratio of Ken's sweets to chocolates became 1:4. How many sweets did Ken buy?. Ans: 68 sweets

Question 6

Curry puff shop sells puffs at \$0.80 each. Offer:Buy 3 get 4th half price. If customer has \$50, how many puffs can he buy if he buys as many as he can. Ans: 71 puff

Question 7

String of 2 big balloons is 90cm
String of 5 small balloons is is 1.2m
If both strings are of the same length, there would be 105 more small balloons than the big balloons. How many balloons are there altogether? Ans: 345

Workings

Click to enlarge

Question 2, 3, 4

Question 5, 6, 7

1. Your answer to question 4 is wrong. 1200 cookies were sold NOT 960. 960 would be the number of chocolate cookies sold.

2. Anonymous @ 1:38AM 24 Oct,

Please provide with explanations if you think it is incorrect.

Thanks
hongjun

3. What are the informations given in Question 1? Is it stated in the question that it is a square?

4. Yes.
Q1 mentions it is a square.

5. Is it also stated in Q1 that the bottom triangle is equilateral triangle?

6. i dont undrstand question 3. can u emphasis?

7. @ Anonymous 1:38 AM, October 24, 2009

You've misinterpreted the question, actually it's your answer that is incorrect.

1200 is the number of cookies baked, not sold.

960 cookies were sold,of which 210 were almond cookies.

Number of chocolate cookies sold
= 960 - 210 = 750

Check : 3/4 x 5/6 x 1200
= 5/8 x 1200
= 750

Do provide your constructive comment. I appreciate that.