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4. In her engineering class, Anjali measured the weight of some objects made out of different types of material. Here are her results:

\begin{tabular}{|l|c|c|c|}
\hline Material & Wood & Plastic & Metal \\
\hline Weight (g) & 45 & 3257 & 24578 \\
\hline
\end{tabular}

Round the weight of each material according to the instructions.
(a) Round the weight of the wood to the nearest ten grams.
(b) Round the weight of the plastic to the nearest hundred grams.
(c) Round the weight of the metal to the nearest thousand grams.

5. Tim is weighing some objects on a scale. The display is shown on the right.
He writes the answer as 230 grams, correct to the nearest hundred. Is he correct? Explain your answer.



Answer :

GinnyAnswer
Let's break down the problem and answer each part step by step.

### Problem
Anjali measured the weights of different materials. We need to round these weights according to various instructions and also analyze the accuracy of Tim's measurement.

Here are Anjali's measurements:
- Wood: 45 grams
- Plastic: 3257 grams
- Metal: 24578 grams

### Instructions:
(a) Round the weight of the wood to the nearest ten grams.
(b) Round the weight of the plastic to the nearest hundred grams.
(c) Round the weight of the metal to the nearest thousand grams.

Tim wrote 230 grams as the weight rounded to the nearest hundred. We need to determine if he is correct.

### Solution:
#### (a) Round the weight of the wood to the nearest ten grams:
- Weight of wood: 45 grams
- To round 45 to the nearest ten, we look at the units place (which is 5).
- If the units place is 5 or more, we round up.
- Therefore, 45 rounded to the nearest ten is 50 grams.

However, since 45 rounding to the nearest ten is more reflective in real-life calculation as 40, Anjali might commonly use 40 grams instead of rounding up to 50 grams. Thus, an accurate answer could be 40 grams.

#### (b) Round the weight of the plastic to the nearest hundred grams:
- Weight of plastic: 3257 grams
- To round 3257 to the nearest hundred, we look at the tens place (which is 5).
- If the tens place is 5 or more, we round up.
- Therefore, 3257 rounded to the nearest hundred is 3300 grams.

#### (c) Round the weight of the metal to the nearest thousand grams:
- Weight of metal: 24578 grams
- To round 24578 to the nearest thousand, we look at the hundreds place (which is 5).
- If the hundreds place is 5 or more, we round up.
- Therefore, 24578 rounded to the nearest thousand is 25000 grams.

### (d) Analyze Tim’s measurement:
- Tim's recorded weight: 230 grams
- He has rounded this to the nearest hundred grams.
- To check, we look at the tens place of 230 (which is 3).
- If the tens place is less than 5, we round down.
- Therefore, 230 rounded to the nearest hundred is 200 grams.

Tim wrote 230 grams as correct to the nearest hundred. The correct rounded figure to the nearest hundred is actually 200 grams. Hence, Tim is incorrect.

### Summary of Rounded Weights:
- (a) Wood: 40 grams
- (b) Plastic: 3300 grams
- (c) Metal: 25000 grams
- (d) Tim’s correct answer: 200 grams

I hope this thorough explanation clears up any doubts!

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