Q&A - PSLE Math

[MathIzzzFun]

mumworks:

Hi


Anyone can help with this question ?

Charlie bought a box of chocolates and sweets. The number of chocolates was 2/3 the number of sweets. Charlie then gave away 5 chocolates and 3 sweets each time he met a friend. After a while, he was left with 20 chocolates and 75 sweets.
(a) How many friends did Charlie meet?
(b) What was the total number of chocolates Charlie had at first?

Thank you.

Hi

at first,
choc : sweets --> 2u : 3u
left 20 choc & 75 sweets,
Gave away, choc : sweets --> 2u-20 : 3u-75 = 5 : 3
cross multiply/equalize:
6u-60 = 15u-375
1u --> 35
Number of friends met --> (2 x 35-20)/5 = 10

can you complete the rest?

cheers.

[tianzhu]

Michaelia0816:

Tianzhu, pls help,

1) Amanda wanted to buy 5 rings, but she was short of $10.75. She decided to buy 3 rings instead and had $4.45 left. What was the cost of 1 ring?

2) James travelled from Town A to Town B which was 306km away. For the first 208km, he drove at the speed of 80km/h. For the remaining journey, he reduced his speed by 24km/h. Find his average speed for the whole journey?

Hi girl

One possible approach for Q1 is to see from this angle.

If Amanda wanted to buy another 2 rings (5-3), she would need (10.75 + 4.45)

Hence, cost of 1 ring ------ 15.2/2 ------ 7.6

As for Q2, find the time taken for the first part (208km) and second part (98km).

Add them up to find the total time taken for the whole journey.

To find the average speed for the whole journey, apply the formula, S =D/T

I’ll leave the details to you.

Best wishes

[Michaelia0816]

Ok, Thanks! There another few question which I do not know how to solve, Tianzhu. So pls help!

Janet had 5 times as much money as Ken. After Janet had given $2450 to Ken, he had thrice as many money as Janet. How much did Ken have at first?

[tianzhu]

Michaelia0816:

Ok, Thanks! There another few question which I do not know how to solve, Tianzhu. So pls help!

Janet had 5 times as much money as Ken. After Janet had given $2450 to Ken, he had thrice as many money as Janet. How much did Ken have at first?

Hi

The total amount of money stays the same.

At first

Janet: Ken ------ 5:1(6) ------ 10:2 (12)

In the end

Janet: Ken ------ 1:3(4) ------ 3:9 (12)

7 units ------ 2450

You may carry on from here.

Best wishes

[jtparent]

Hi, pse assist on the 2 quest:


1. Miss Wang got her pupils to form a circle. They stood at an equal distance apart from each other and were numbered in order. The pupil with number 5 stood directly across from the pupil with number 19. How many pupils were there in the circle?

2. Tan, Lim and Wong had some pens to sell. Tan had the least number of pens. Wong’s number of pens was 30% less then Lim. After Tan and Lim had each sold 50% of their pens, Lim had 95 more pens than Tan. If the 3 men had a total of 330 pens left, what was the total number of pens they had at first?

TIA

[tianzhu]

jtparent:

Hi, pse assist on the 2 quest:

1. Miss Wang got her pupils to form a circle. They stood at an equal distance apart from each other and were numbered in order. The pupil with number 5 stood directly across from the pupil with number 19. How many pupils were there in the circle?

Hi

Start with a simple visual representation.

Number of pupils between 5 and 19 ------- 14-1 ------13

Number of pupils in circle ------- 13+13+2 ------- 28

Best wishes

[Michaelia0816]

To Tianzhu, pls help with my math booklet HW last question,

OPQRS is part of a circle of radius 10cm. OPR and OQS are quarter circles. The area of the shaded part OQR is 40cm2, and the perimeter of the shaded part OQR is 28cm.

(Go to this web below for the picture of the figure)
http://t.co/4VZEguWj

For each following, use the calculator value of pi to find,
(a) the area of the figure OPQRS, correct to 2 decimal places,
(b) the perimeter of the figure OPQRS, correct to 2 decimal places

[tianzhu]

jtparent:

2. Tan, Lim and Wong had some pens to sell. Tan had the least number of pens. Wong's number of pens was 30% less then Lim. After Tan and Lim had each sold 50% of their pens, Lim had 95 more pens than Tan. If the 3 men had a total of 330 pens left, what was the total number of pens they had at first?

Hi

Lim ------- 10 units

Wong ------ 7 units

After Tan and Lim had each sold 50% of their pens,

Lim ------- 5 units

Tan ------- 5 units – 95

Wong ------- 7 units

17 units – 95 ------- 330

1 unit ------ 25

I’ll leave it to you to work out the rest of the details. The answer is 485.

Best wishes

[jtparent]

tianzhu:

jtparent:

2. Tan, Lim and Wong had some pens to sell. Tan had the least number of pens. Wong's number of pens was 30% less then Lim. After Tan and Lim had each sold 50% of their pens, Lim had 95 more pens than Tan. If the 3 men had a total of 330 pens left, what was the total number of pens they had at first?

Hi

Lim ------- 10 units

Wong ------ 7 units

After Tan and Lim had each sold 50% of their pens,

Lim ------- 5 units

Tan ------- 5 units – 95

Wong ------- 7 units

17 units – 95 ------- 330

1 unit ------ 25

I’ll leave it to you to work out the rest of the details. The answer is 485.

Best wishes

Thanks Tianzhu for the prompt 2 ans reply! Have a great wkend!
cheers

[tianzhu]

Michaelia0816:

To Tianzhu, pls help with my math booklet HW last question,

OPQRS is part of a circle of radius 10cm. OPR and OQS are quarter circles. The area of the shaded part OQR is 40cm2, and the perimeter of the shaded part OQR is 28cm.

(Go to this web below for the picture of the figure)
http://t.co/4VZEguWj

For each following, use the calculator value of pi to find,
(a) the area of the figure OPQRS, correct to 2 decimal places,
(b) the perimeter of the figure OPQRS, correct to 2 decimal places

Hi

I believe you merely just wanted to confirm your answers.

They are 117.10 sq cm and 43.42cm.

Bye and have a nice weekend.

Best wishes