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David Q/R
Answers (93)
The distance between the X coordinates is 2 minus -5 = 7. The distance between the Y coordinates is 2 minus 1 = 1. Those two distances are the base and height of a right-angled triangle, so to get the hypoteneuse, use Pythagoras: that gives you that the
With no knowledge of the trigonometry of triangles, argue it like this. The question wouldn't have been asked if there wasn't a unique answer, so the answer must be the same regardless of whereabouts above the base the apex is - including the special case
Four will ensure you've extracted at least two of the same color - but unless you turn the light on there's still no guarantee that you'll get two of the same color on you feet. Is that why it's a riddle?
I think there's posibly a piece of information missing in the question as you've stated it, which is that you're only supposed to be looking at the function between the values X = -1 and X = +1, because the function is discontinuous at both of those
Assuming that's 1, 1, 2, 3, 5... it's the Fibonacci sequence, in which X(i) = X(i-1) + X(i-2), where X(1) = X(2) = 1. So 1+1=2, 1+2=3, 2+3=5, 3+5=8, 5+8=13 etc etc.
I think you're asking whether a t-test is appropriate when your data consists of a binary response, i.e. a Success or a Failure, and you've got a very small number of responses. If so, the answer is no it isn't: it seems to me you ought to be looking at
I'm going to assume that you mean the average annual salary is $30k, not $300k - because $300k sounds a bit excessive to me, even for Americans! If so, the proportion of Americans who earn below $22k should be the area to the left of ($22k-$30k)/$7k =
You're welcome!
a) This one should state that the mean of the observed values will be approximately Normal, not that the distribution will be approximately Normal. b) I don't know what the 68-95-99.7 rule actually is, but it'll probably say something about 68%, 95% and
(x-5)/3 = 1, so multiply both sides of the equation by 3, and you'll get (x-5) = 3. Now add 5 to both sides of the equation and you'll get x = 3 + 5 = 8. And that's your answer.
More information is needed please. How does x in the above equation relate to either a coin or a pouch?
You don't even need a set of Normal tables to answer this one. Just remember that the total area under the curve is 1; note that you've been asked to find the proportion of the distribution in the larger section, and then look at the four options. How many
Because all four parts of the question involve the same set of calculations, I suggest you first work out all sixteen of the various probabilities, check that they add up to one (because if they don't, the chances are that you'll get several parts of the
It's just 0.05 x 0.05 = 0.0025. The fact that they were both sold during a given hour is irrelevant to the calculation, BUT you're assuming when you perform that calculation that the returning of one item is independent of whether or not another one is
The standard error of the mean of a sample of N is the population standard deviation divided by sqrt(N), so if the second parameter of your N(188, 41) is the population standard deviation, the SEM should be 1.297. So you need to find out how many standard
The sum of the angles of a triangle is 180 degrees. Yours is an isosceles triangle, and the vertical angle is four times the size of a base angle - so you've got two base angles, plus four more base angles in the vertical angle. That's six base angles in
The standard error of the mean (SEM) is a measure of how well the sample mean is estimated - so if you increase the sample size, the standard error of the mean should get smaller. Specifically, if S is the standard deviation of the sample, then the SEM =
Let's assume the numbers are large enough so we can use a Normal approximation to the binomial distribution here. The mean and standard deviation of the binomial distribution will be Np and sqrt(Np(1-p)) respectively, where in this example N = 128 and p =
Let the number of servings of beef be B, and let the number of servings of mash be M. Then we know that: 20B + 2M = 29 11B + 25M = 61 Multiply the first equation by 25, and the second one by 2 to get: 500B + 50M = 725 22B + 50M = 122 Subtract the second
You won't be able to determine x and y uniquely from just a single equation: you would need two equations to do that. The best you can do with just one equation is to work out x in terms of y, or y in terms of x. The way you do that is to get all the x's
I'm going to try to infer a lot here, because the question is so obscure. I assume you're being asked to work out what the denominator of a fraction is when you're presented with the equivalent decimal. So suppose you're given a decimal number like 0.42,
Permutations and combinations? xP1 is the number of ways in which you can take one item out of x items - and that's just x. So for example the number of ways in which you can take one item from 10 is going to be 10. It doesn't matter whether order is
Add 1 to both sides, and then add (T-3) to both sides. That gets you 6 = 3(T-3). Divide both sides by 3 and you'll have 2 = (T-3). Then add 3 to both sides, and you've got T, which presumably is what you want, yes?
Suppose the number is ABC. Then if C is twice A, we know that A can't be any greater than 4. So the number must be one of the following: 1B2, 2B4, 3B6 or 4B8. When rounded to the nearest hundred it's 500, so it must be the last of those four, i.e. 4B8. If
x + y = 5.3 x - y = 1.7 So add the equations together: 2x = 7.0 x = 3.5 But x + y = 5.3, so y = 1.8 Check it: x times y = 6.3. Correct!
Asking for the gcf implies that there ought to be at least two things that you're trying to factorize (because the gcf is the "greatest common factor"), whereas here there's only one. I think part of the question must have been lost somewhere.
The temperature will drop on an exponential decay curve, i.e. a curve with the equation F = 53 + (185-53)exp(-a.t) = 53 + 132.exp(-a.t) for some parameter a which we need to determine. We know that because at t = 0, F = 185, and as t increases without
Ask for what t is -16t^2 + 34t + 15 = 0? Use the usual quadratic formula for that one: x = (-b +/- sqrt(b^2 - 4ac)) / 2a sqrt(b^2 - 4ac) = 46, so the answer is either a negative number or 80/32 = 10/4 = 2.5. So that's the answer: two and a half seconds.
That's what I get too. It doesn't look so much that way, does it!
I think what you're being asked is this. There's some polynomial - let's call it f(x) - that when divided by (x + 10) equals (x^2 - 6x + 10) with remainder -1. What is f(x)? If I'm right, then we should be able to find it by multiplying (x^2 - 6x + 10) by
X is exponentially distributed, so the probability density function f(x) = m.exp(-m.x), where E(X) = 1/m. You're told that the expected value is 10 mins, so 1/m = 10, so m = 1/10 = 0.1. So what you need to calculate is the integral of the pdf between 5
Suppose he's got D ducks and C cows. Then we know that D + C = 22. Now: a duck has two legs, and a cow has four. So 2D + 4C = 56, which is the total number of legs. But D + C = 22, so 2D + 2C = 44. So if you subtract this equation from the one that tells
I agree with all your answers, if by "d" you mean the left hand side of the equation. Regarding no. 7, I suggest you do something like this: Each side of the equation inside the "absolute bars" could be either positive or negative. Try assuming that each
a(x+1) = b, so divide both sides by a: x+1 = b/a, so subtract 1 from both sides: x = b/a - 1.
Please tell us how many owners there are in total, and how many horses are owned by each of them.
An obvious candidate is 5, so if you divide 555 by 5 you'll get 111. That's divisible by 3 (because the sum of the digits is divisible by 3, which is a useful quick check), so do that and you'll get 111/3 = 37. But 37 is a prime number, so you won't be
It should be 2 x 3 x 5 x 7, I think, i.e. the product of the first four prime numbers.
You're welcome!
Let my age now be A, and let Mum's age now be M. Then we know that: A = M/3, so 3A = M A-8 = (M-8)/5, so 5A-40 = M-8 but M = 3A, so 5A-40 = 3A-8 so 2A = 40-8 = 32 so A = 16 so M = 48. Check it: A is one-third of M, and eight years ago I would have been 8
To get it right, make sure you distinguish between the first and second throw. If you do that, you'll see that there are 36 distinct outcomes: (1, 1), (1, 2), (1, 3), ... (6, 4), (6, 5) and (6, 6). They're all equally likely with probability 1/36, so how
There are 900 three-digit numbers in total (100 to 999 inclusive), and every odd-numbered one is even, i.e. 1st = 100, 3rd = 102, 5th = 104, 7th = 106 etc. There are as many odds and evens in 900 consecutive integers, so exactly half of them are even, i.e.
It looks like a Venn diagram problem to me - which is a pity because I can't draw a Venn diagram here. Never mind: I'll try to manage with just the numbers. Pr(EuF) = P(E) + P(F) - P(EnF) = 0.55 + 0.55 - Pr(EnF) = 0.85, so Pr(EnF) = 1.10 - 0.85 = 0.25.
If the plane is travelling at 15 miles per minute, it'll take 500/15 = 100/3 minutes = 100/(60x3) hours = 5/9 hours to cover 500 miles. In that 5/9 hours, the car will travel (5/9) x 55 = 30.556 miles. (I've checked it three times because the numbers look
Not quite, I think. Call the number of kilos of apples A, and the number of kilos of berries B. Then you know that: 4A + B = $5.75 2A + B = $3.25 so subtract the second equation from the first, and you'll get 2A = $2.50, so A = $1.25. Subtract the 2A =
(I think 7485 will also do it: an explanation of the logic is supplied in response to Amy's posting of this question.)
Already tackled - see your other post.
The number is odd, and divisible by 5 - so the final digit must be 5. The largest digit is in the tens place, but isn't the largest digit, and no digits are repeated - so it must be 6, 7 or 8. The digit in the hundreds place is half the digit in the tens
Please tell us what Scenario 1-4 is.
I imagine you'd want to keep the card with the largest number of factors. 24 has got the following factors: {2, 3, 4, 6, 8, 12}, so there are 6 of them. 30 has got {2, 3, 5, 6, 10, 15}, so there are 6 of them. 35 has got {5, 7} so there are just 2. 36 has
No problem - but you'll still need to be able both to measure a distance and to calculate an angle. Measure the distance between the bottom of the flagpole and a point some convenient distance away - it doesn't really matter how far, but say it's Y meters.
