The graph below depicts the price of tomatoes as a function of quantity, with each line representing the prices at different shops.
Where is it cheaper to buy 7 kg of tomatoes?
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The graph below depicts the price of tomatoes as a function of quantity, with each line representing the prices at different shops.
Where is it cheaper to buy 7 kg of tomatoes?
Let's look at the red line:
The X-axis shows us the quantity, we'll locate 7 kg and from it draw a vertical line to the line - mark a point.
From this point we'll draw a horizontal line to the Y-axis which shows the price and we'll see that 7 kg costs 8 NIS.
Let's look at the blue line:
The X-axis shows us the quantity, we'll locate 7 kg and from it draw a vertical line to the line - mark a point.
From this point we'll draw a horizontal line to the Y-axis which shows the price and we'll see that 7 kg costs 10 NIS.
Therefore it's better to buy at the red store, it's cheaper.
In the red shop
Look at the linear function represented in the diagram.
When is the function positive?
Look at the color coding in the graph! The problem mentions 'red shop' and 'blue shop', so match the line colors to identify each store's pricing.
If the lines intersect exactly at x = 7, both shops would charge the same price for 7 kg. In that case, either shop would be equally good!
Drawing vertical and horizontal guide lines ensures accuracy! Estimating by eye often leads to reading errors, especially when the graph points fall between grid lines.
The slope represents the price per kg. A steeper line means higher cost per additional kilogram. The red line has a gentler slope, so it's cheaper per kg.
Absolutely! This vertical-then-horizontal reading method works for any x-value on the graph. Just find your quantity on the x-axis and follow the same steps.
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