PSAT Math : Arithmetic
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Example Question #1221 : Sat Mathematics
Each wooden chair that a carpenter makes requires $20 worth of supplies. He then sells the chairs for $50 each. The carpenter recently discovered a new supplier that would allow him to spend 25% less on supplies. If he doesn't change his selling price, by what percent could the carpenter increase his profit by using the new supplier?
Using $20 worth of supplies and selling the chairs for $50 each, the carpenter is originally making a profit of $30 per chair.
The new supplier would reduce costs by 25% or 1/4. One-fourth of $20 is $5, so the new supplier would be $5 less, or $15.
If the selling price is the same ($50), then the carpenter would now make a profit of $35 per chair, a change of $5.
To calculate percent increase, divide the actual change in profit by the original profit amount, and multiply the result by 100%:
(Actual Change ÷ Original Amount) * 100% = 5/30 * 100% = 500%/30 = 16.7%
Example Question #1222 : Sat Mathematics
A craftsman builds a cabinet. He pays $250 to buy the wood and miscellaneous materials for the cabinet. He spends 20 hours building the cabinet. If he values his time at $40 per hour and expects a profit margin of 50% above labor and materials, how much should he charge for the cabinet?
Total Cost = Material Cost + Labor Cost + Profit
Labor Cost = $40/hour * 20 hours = $800
Profit Margin of 50% = Cost x 0.50 = $1050 x 0.50 = $525
Total Cost = $250 + $800 + $525 = $1575
Example Question #1223 : Sat Mathematics
The cost of manufacturing a single teddy bear is $6.25. A teddy bear company sells 200 bears for $1750. What is the profit percentage per single bear?
72%
140%
28%
60%
40%
40%
First we must find out what the price is for one teddy bear, manufactured by this company. Thus we divide 1750 by 200 and find that each bear costs $8.75. To find out the profit per bear, we divide 8.75 by 6.25 to arrive at 1.4. The bears are thus sold for 140% of what it costs to make them, giving a 40% profit.
Example Question #22 : Percentage
If there is a 10% sale on an item, and then 9% sales tax is applied to that after-sale price, then what is the total cost of the item including tax as a percentage of its pre-sale sticker price?
101%
99%
81.9%
98.1%
99.2%
98.1%
A 10% sale means that the post-sale price of the item is now 90%, or 0.9 of the original cost of the item. We then apply 9% sales tax by multiplying the 0.9 by 109%, or 1.09. 0.9 * 1.09 = .981, so the total cost of the item is 98.1% of the original pre-sale sticker price.
For percentage problems that do not deal with a specific starting number, it is always helpful to plug in 100 for the starting number. Here, we would then have a post-sale price of 90 dollars, and if we calculate the sales tax for the 90-dollar item it would be 90 * 0.09 = $8.10. THis gives us a total cost of 90 + 8.10 = $98.10, or 98.1% of the original 100-dollar price.
Example Question #1 : How To Find The Amount Of Sales Tax
Cynthia buys 2 shirts, each costing $35, a pair of pants for $40 and a belt for $18. At the register the total she owes is $138.24. What is the rate of sales tax in her state?
To find the amount of sales tax, take the difference in the total before and after tax 
Example Question #1 : How To Find The Amount Of Sales Tax
A certain state charges sales tax at a rate of 8.75% per dollar spent. John spends $127.50 total, including tax, on clothes. What was the total price of the clothing before tax was added?
Since we know the total price with tax, we simply need to work backwards to remove the tax from the total price and find the price of the clothing itself. This can be done as follows:
Clothing Price or C = Total price / 1 + tax rate
C = $127.50/(1 + 0.0875) = $117.24
Example Question #2 : How To Find The Amount Of Sales Tax
Jack is at the grocery store. He buys 
Jack's groceries are not taxed, so they cost 
We will add the two together
Example Question #3 : How To Find The Amount Of Sales Tax
Harry, on his first lunch date with Sally, decides to put the entire bill on his credit card. If the bill came to $28 and Harry wants to leave an 18% tip, what is the total amount that he should pay?
To find an 18% increase, multiply by 1.18.
Example Question #1 : How To Find The Amount Of Sales Tax
Lisa just bought a desktop computer. The computer cost $1500, the keyboard cost $100, and the mouse cost $25. If the local sales tax is 7%, what was the total cost of her purchases?
Total Tax = 
Total Cost = Computer + Keyboard + Mouse + Tax =
Example Question #5 : How To Find The Amount Of Sales Tax
Mike spent $30 on food and $50 on non-food products in the supermarket. There's a sales tax of 10% on non-food products only. How much did Mike spend in total at the supermarket?
Since sales tax is only applicable to non-food products only, we can multiply 50 by 1.1 to get the total price of non-food products. In this case, it is $55. Add this value to the $30 spent on food for a total of $85.
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