Question :
The figure below, not drawn to scale, is made up of 3 squares. Find the area of the shaded parts
Ans :
Area of Big Rectangle = 18cm x 14cm
252 cm2
Area of unshaded Big triangle = 1/2 * 14cm *
16cm
= 112 cm2
Area of unshaded small triangle = 1/2 * 8cm * 8cm
= 32 cm2
Area of Small unshaded Rectangle = 2cm x 6cm
= 12 cm2
Area of shaded parts = 252cm2 - 112cm2 - 32cm2 - 12cm2
= 96 cm2
Ans : 96 cm2
Explanation :
This question require a little thinking. As the slope of the shaded parts extended from one square to the other, it do not cut perfectly at the corner of the 10cm square. Therefore you will need to extend the boundary into a bigger rectangle and minus off the unshaded portion. This type of question will train the students to think unconventionally. The diagram is illustrated separately at the bottom.
Thursday 23 May 2013
Friday 17 May 2013
More Word Problem - 2 scenerios
Question :
Mr Tan bought a bag of sweets for his class. If he gives 13 sweets to each of his pupils equally, he has 4 sweets left. If he gives 8 sweets to each of his pupils equally, he has 214 sweets left. How many pupils are there in his class?
Method 1 :
Differences in sweets to each pupils 13 - 8 = 5
Difference in total of sweets left 214 - 4 = 210
Nos. of pupils = Difference in total of sweets left / Differences in sweets to each pupils
= 210 / 5 = 42
Ans : 42 pupils
Methods 2 :
Let the Nos. of pupils in the class be 1 unit
Total sweets = sweet gave + sweets left
13 units + 4 = 8 units + 214
13 units - 8 unit
214 - 4
5 units
210
1 unit
210 / 5 = 42
Ans : 42 pupils
Remarks :
Many students approach to solve this type of problem with guess & check method. Although it is one of the approve ways of solving the problem, personally, I feel it take more time with guess & check method. With the above 2 methods, it will give student more time to check their test papers by solving the problem faster. It is also my advice to student that whenever problem need to be solve by guess and check. They should reserve it to the last and spend their time firstly on question that they can solve quickly.
Mr Tan bought a bag of sweets for his class. If he gives 13 sweets to each of his pupils equally, he has 4 sweets left. If he gives 8 sweets to each of his pupils equally, he has 214 sweets left. How many pupils are there in his class?
Method 1 :
Differences in sweets to each pupils 13 - 8 = 5
Difference in total of sweets left 214 - 4 = 210
Nos. of pupils = Difference in total of sweets left / Differences in sweets to each pupils
= 210 / 5 = 42
Ans : 42 pupils
Methods 2 :
Let the Nos. of pupils in the class be 1 unit
Total sweets = sweet gave + sweets left
13 units + 4 = 8 units + 214
13 units - 8 unit
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-JwEWukfB8FvNFKIZyfMG7v6hQ2aONz3fFfaNPZicmCH0UlW41S2hroRoYclzA7qS_BVYlgVNG2NG2UbL6ML0MKDtyF3Ix9xUjl0xV7KzSKpJDA6lP6Lu1PY73K9-SqE_dtTE6pjHO3U/s1600/Arrow.png)
5 units
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-JwEWukfB8FvNFKIZyfMG7v6hQ2aONz3fFfaNPZicmCH0UlW41S2hroRoYclzA7qS_BVYlgVNG2NG2UbL6ML0MKDtyF3Ix9xUjl0xV7KzSKpJDA6lP6Lu1PY73K9-SqE_dtTE6pjHO3U/s1600/Arrow.png)
1 unit
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj-JwEWukfB8FvNFKIZyfMG7v6hQ2aONz3fFfaNPZicmCH0UlW41S2hroRoYclzA7qS_BVYlgVNG2NG2UbL6ML0MKDtyF3Ix9xUjl0xV7KzSKpJDA6lP6Lu1PY73K9-SqE_dtTE6pjHO3U/s1600/Arrow.png)
Ans : 42 pupils
Remarks :
Many students approach to solve this type of problem with guess & check method. Although it is one of the approve ways of solving the problem, personally, I feel it take more time with guess & check method. With the above 2 methods, it will give student more time to check their test papers by solving the problem faster. It is also my advice to student that whenever problem need to be solve by guess and check. They should reserve it to the last and spend their time firstly on question that they can solve quickly.
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