Answer: x-7
Step-by-step explanation:
Answer:
April took out a loan of $600 and paid it back with simple interest of $60 after 5 years. The formula to calculate interest is given the principal and the time and the interest rate is . For this problem we have to find the interest rate given . To archive that , we can just solve the equation making the interest rate the subject of the formula as shown below,
I= Prt
=> r= I/Pt
=> r= 60/600x5 = 1/50
The interest rate is 1/50 or 0.02 as a decimal. The interest rate is 2% as a percentage.
I don't know what the "six-step method" is supposed to be, so I'll just demonstrate the typical method for this problem.
Let <em>x</em> be the amount (in gal) of the 50% antifreeze solution that is required. The new solution will then have a total volume of (<em>x</em> + 60) gal.
Each gal of the 50% solution used contributes 0.5 gal of antifreeze. Similarly, each gal of the 30% solution contributes 0.3 gal of antifreeze. So the new solution will contain (0.5 <em>x</em> + 0.3 * 60) gal = (0.5 <em>x</em> + 18) gal of antifreeze.
We want the concentration of antifreeze to be 40% in the new solution, so we need to have
(0.5 <em>x</em> + 18) / (<em>x</em> + 60) = 0.4
Solve for <em>x</em> :
0.5 <em>x</em> + 18 = 0.4 (<em>x</em> + 60)
0.5 <em>x</em> + 18 = 0.4 <em>x</em> + 24
0.5 <em>x</em> - 0.4 <em>x</em> = 24 - 18
0.1 <em>x</em> = 6
<em>x</em> = 6/0.1 = 60 gal
Answer:
The standard deviation for the number of defective parts in the sample is 1.88.
Step-by-step explanation:
The sample is with replacement, which means that the trials are independent, and thus, the binomial probability distribution is used to solve this question.
Binomial probability distribution
Probability of exactly x successes on n repeated trials, with p probability.
The expected value of the binomial distribution is:
The standard deviation of the binomial distribution is:
68 defective out of 400:
This means that
From the shipment you take a random sample of 25.
This means that
Standard deviation for the number of defective parts in the sample:
The standard deviation for the number of defective parts in the sample is 1.88.
Answer:
17 animals
Step-by-step explanation:
Rachel has a collection of 40 stuffed animals
3/8 are bears
= 3/8 ×40
= 120/8
= 15
1/5 are dogs
= 1/5×40
= 40/5
= 8
15+8
= 23
Therefore the number of animal she have left can be calculated as follows
= 40-23
= 17
Hence there are 17 animals left