Unit 19
Cabar Minda
Sebiji tembikai seberat 5 kg mengandungi lebih kurang 4 500 mℓ air.
Anggarkan isi padu air dalam 1 kg tembikai itu.
估算 = anggaran；大约 = lebih kurang；西瓜 = tembikai
这是一道动脑题：一个 5 kg 的西瓜大约含 4 500 mℓ 的水，问 1 kg 西瓜大约含多少水。水果里面有很多水，西瓜特别多。我们假设每 1 kg 的西瓜含水一样多，就可以从“5 kg 的水”推出“1 kg 的水”。
例子：一个 2 kg 的西瓜，水大约是 5 kg 西瓜的一小半。
注意：题目里有两种单位，kg 是质量，mℓ 是液体体积，不能混在一起相加。
estimate = anggaran; about = lebih kurang; watermelon = tembikai
This is a thinking puzzle: a 5 kg watermelon holds about 4 500 mℓ of water, and we want to know roughly how much water is in 1 kg of it. Fruit contains a lot of water, and watermelon contains even more. If we assume every kilogram holds the same amount of water, we can work out the water in 1 kg from the water in 5 kg.
Example: a 2 kg watermelon would hold a bit less than half the water of the 5 kg one.
Watch out: there are two kinds of unit here, kg for mass and mℓ for liquid volume, and they must never be added together.
Langkah 1
Faham soalan
5 bahagian sama banyak
Diketahui
5 kg → 4 500 mℓ
Dicari
1 kg → ? mℓ
已知和要找 = diketahui dan dicari；条形图 = model bar
先把题目画成图。5 kg 的西瓜分成 5 格，每格是 1 kg，每格里的水一样多。5 格合起来是 4 500 mℓ 水。要找的是其中 1 格有多少 mℓ。画了图就看得出：这是把 4 500 平均分成 5 份。
例子：4 个苹果共 1 kg，就是把 1 kg 平均分成 4 份。
注意：5 格要画得一样大，因为假设每 1 kg 的含水量一样。
given and to find = diketahui dan dicari; bar model = model bar
First turn the question into a picture. The 5 kg watermelon is drawn as 5 equal boxes, one box for each kilogram, and each box holds the same amount of water. All 5 boxes together hold 4 500 mℓ. We want the number of millilitres in just one box. The picture shows this is sharing 4 500 equally into 5 parts.
Example: 4 apples weighing 1 kg in total means sharing 1 kg into 4 equal parts.
Watch out: draw the 5 boxes the same size, because we assume every kilogram holds the same amount of water.
Langkah 2 · Cuba
Ayat matematik yang manakah betul untuk mencari air dalam 1 kg?
选对算式 = pilih ayat matematik
把 4 500 mℓ 水平均分给 5 个 1 kg，用除法，而且是“水 ÷ 公斤数”：4 500 mℓ ÷ 5。
例子：3 kg 的橙子约有 2 400 mℓ 水，1 kg 就是 2 400 ÷ 3。
注意：5 ÷ 4 500 是倒过来除，单位也倒了；4 500 × 5 是求 25 kg 的水，越算越多。
choosing the right number sentence = pilih ayat matematik
Sharing 4 500 mℓ of water equally among 5 kilograms is division, with the water divided by the number of kilograms: 4 500 mℓ ÷ 5.
Example: if 3 kg of oranges hold about 2 400 mℓ of water, 1 kg holds 2 400 ÷ 3.
Watch out: 5 ÷ 4 500 divides the wrong way round and mixes up the units, while 4 500 × 5 would be the water in 25 kg.
Langkah 2
Bahagi untuk cari 1 kg
4 500 ÷ 5 = 900
4 000 ÷ 5 = 800 · 500 ÷ 5 = 100 · 800 + 100 = 900 mℓ
Semak: 900 × 5 = 4 500 ✓
归一 = cari nilai untuk 1 unit
4 500 ÷ 5 可以拆开来算：4 000 ÷ 5 = 800，500 ÷ 5 = 100，合起来 900。所以 1 kg 西瓜大约含 900 mℓ 水。再用乘法验算：900 × 5 = 4 500，对上了。题目说“大约”，所以答案也是大约 900 mℓ。
例子：6 kg 的南瓜约有 5 400 mℓ 水 → 5 400 ÷ 6 = 900 mℓ。
注意：答案的单位是 mℓ，不是 kg，因为我们求的是水的体积。
finding the amount for one unit = cari nilai untuk 1 unit
4 500 ÷ 5 can be split up: 4 000 ÷ 5 = 800 and 500 ÷ 5 = 100, which together make 900. So 1 kg of watermelon holds about 900 mℓ of water. Check with multiplication: 900 × 5 = 4 500, which matches. The question says about, so the answer is also about 900 mℓ.
Example: 6 kg of pumpkin holding about 5 400 mℓ of water gives 5 400 ÷ 6 = 900 mℓ per kilogram.
Watch out: the answer is in mℓ, not kg, because we are finding a volume of water.
Langkah 3 · Guna
Berapakah anggaran air dalam 3 kg tembikai yang sama?
用一份去推几份 = guna nilai 1 kg
先求出 1 kg 约 900 mℓ，就可以算任何公斤数。3 kg 是 3 个 1 kg：900 × 3 = 2 700 mℓ = 2 ℓ 700 mℓ。
例子：2 kg 的同一种西瓜 → 900 × 2 = 1 800 mℓ。
注意：1 ℓ 500 mℓ 是用 4 500 ÷ 3，把 5 kg 的水当成 3 份；13 ℓ 500 mℓ 是 4 500 × 3。
using one share to find several = guna nilai 1 kg
Once we know 1 kg holds about 900 mℓ, we can work out any number of kilograms. 3 kg is three lots of 1 kg: 900 × 3 = 2 700 mℓ = 2 ℓ 700 mℓ.
Example: 2 kg of the same watermelon → 900 × 2 = 1 800 mℓ.
Watch out: 1 ℓ 500 mℓ comes from 4 500 ÷ 3, which wrongly splits the 5 kg water into 3 parts, and 13 ℓ 500 mℓ is 4 500 × 3.
Cuba lagi
Air dalam 1 kg buah
配对每公斤的水 = padankan air dalam 1 kg
每一个都是“水 ÷ 公斤数”。橙 3 400 ÷ 4 = 850 mℓ；番茄 2 820 ÷ 3 = 940 mℓ；黄梨 1 720 ÷ 2 = 860 mℓ；木瓜 4 400 ÷ 5 = 880 mℓ。算完可以用乘法验算，例如 850 × 4 = 3 400。
例子：黄瓜 2 kg 约 1 900 mℓ → 1 900 ÷ 2 = 950 mℓ。
注意：每 1 kg 的水都不到 1 000 mℓ，算出比 1 000 mℓ 多就要检查。
matching water per kilogram = padankan air dalam 1 kg
Each one is water divided by kilograms. Oranges: 3 400 ÷ 4 = 850 mℓ; tomatoes: 2 820 ÷ 3 = 940 mℓ; pineapple: 1 720 ÷ 2 = 860 mℓ; papaya: 4 400 ÷ 5 = 880 mℓ. Each answer can be checked by multiplying, for example 850 × 4 = 3 400.
Example: 2 kg of cucumber with about 1 900 mℓ of water → 1 900 ÷ 2 = 950 mℓ.
Watch out: none of these fruits has 1 000 mℓ of water per kilogram, so an answer above 1 000 mℓ needs checking.
Ringkasan
Syabas!
jumlah air ÷ bilangan kg = air dalam 1 kg
Lukis bahagian sama banyak. Bahagi isi padu air dengan bilangan kg untuk dapat 1 kg. Guna nilai 1 kg untuk anggar kg yang lain, dan semak dengan darab.
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