100 envelopes cost $0.70 how much would it be for 250
The Correct Answer and Explanation is:
To calculate the cost of 250 envelopes when 100 envelopes cost $0.70, we can set up a simple proportion or use unit rate multiplication.
✅ Correct Answer: $1.75
🧮 Step-by-Step Explanation:
- Determine the cost per envelope: $0.70100=$0.007 per envelope\frac{\$0.70}{100} = \$0.007 \text{ per envelope}
- Multiply the unit cost by 250: 250×$0.007=$1.75250 \times \$0.007 = \$1.75
So, 250 envelopes cost $1.75.
Explanation:
When faced with a problem involving proportional costs, the key idea is to determine how much one item costs and then scale that up to however many items you need. This is known as the unit rate method, and it’s a fundamental concept in both arithmetic and real-life budgeting situations.
In this case, we’re told that 100 envelopes cost $0.70. That means each individual envelope costs a fraction of a cent. To find the cost of a single envelope, divide the total price by the number of envelopes: $0.70÷100=$0.007\$0.70 ÷ 100 = \$0.007
So, one envelope costs seven-tenths of a cent.
Next, you want to know how much 250 envelopes would cost. Since each envelope costs $0.007, you multiply that amount by 250: $0.007×250=$1.75\$0.007 × 250 = \$1.75
This tells you the total cost of 250 envelopes is $1.75.
Alternatively, you can think in terms of proportional scaling. If 100 envelopes cost $0.70, then 200 envelopes (double the quantity) would cost double the price: $1.40. Then you just need to add the cost of 50 more envelopes. Since 100 envelopes cost $0.70, 50 envelopes cost half of that, or $0.35. Adding $1.40 + $0.35 also gives you $1.75.
Understanding how to scale quantities proportionally is crucial not just in math class but also in shopping, budgeting, and comparing deals. It helps ensure accuracy and prevents overpaying.
