Question 863165: 1)Find all values of k that ensure that the given equation has exactly one solution.
kx2 + 26x + k = 0
k = (smaller value)
k = (larger value)
2)What quantity of pure acid must be added to 300 mL of a 25% acid solution to produce a 70% acid solution?
3)Mary has $3.00 in nickels, dimes, and quarters. If she has twice as many dimes as quarters and negative six more nickels than dimes, how many coins of each type does she have?
4)A coffee merchant sells a customer 2 lb of Hawaiian Kona at $5.50 per pound. The merchant's scale is accurate to within ±0.09 lb. By how much could the customer have been overcharged or undercharged because of possible inaccuracy in the scale? (Round your answer to the nearest whole cent.)
5)It is estimated that the annual cost of driving a certain new car is given by the formula
C = 0.38m + 2100
where m represents the number of miles driven per year and C is the cost in dollars. Jane has purchased such a car and decides to budget between $6660 and $8180 for next year's driving costs. What is the corresponding range of miles that she can drive her new car?
6)
Answer by josgarithmetic(39617)   (Show Source):
You can put this solution on YOUR website! Too many questions in one posting, but there is a lesson which will help with the mixture problem, and I give here most of the solution for your quadratic equation problem.
See this for the mixture problem: Mixture percents: One part known, other part unknown
The quadratic, k value question:
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The discriminant must be 0, if the equation has exactly 1 solution.
Given  , the discriminant is  .
 or 
Number 4 Question:
How many pounds bought, if no scale error? 2 pounds.
If the scale undershoots, then reading was 2-0.09 pounds, 1.91 pounds.
If scale overshoots, then reading was 2.09 pounds.
The expectation is $11.00 dollars for 2 pounds of coffee.
The undershot at 1.91 pounds SHOULD cost  dollars. Payment is 45 cents too much.
The overshot at 2.09 pounds SHOULD cost  dollars. Payment is 50 cents too little.
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