# Tagged Questions

Use this tag when you want to determine the thinking that is needed to solve a certain type of problem, as opposed to looking for a specific answer to a question.

14 views

### Mixture & Alligation problem

In what ratio must a person mix three kinds of wheat costing him 1.20,1.44 and 1.74 dollars per kg., so that the mixture formed is worth 1.41 dollars per kg? a)11:77:7 b)12:7:7 c)ratio other than a ...
18 views

### Simple ratio problem

I am currently working through some tests for graduate schemes and I am finding the maths tests relatively okay despite the time restrictions. However, I have come across one basic ratio question that ...
125 views

### Explanations for why someone cannot divide by $x-4$ for $x(x-4)=x(x-4)(x-5)$

A student divides both sides by $x-4$ and lost a solution $x=4$. How could you explain to the student that they are not allowed to divide by $x-4$ Here is the problem: $x(x-4)=x(x-4)(x-5)$ I am ...
39 views

### What is the speed of the car given the time taken to receive an echo?

I am trying to solve this question- The driver of an engine produced a whistle sound from a distance $800m$ away a hill to which the engine was approaching.The driver heard the echo after ...
45 views

56 views

### Solving diophantine equations

So the equation I am trying to solve is $x^2=y^4-77$ So far I have rearranged and factorised the equation to get: $$(y^2-x)(y^2+x)=77$$ But I am really unsure of how to solve it from here. Thanks in ...
27 views

### Understanding foundational terms: notions, objects and meta-objects

I am trying to take my problem solving skill to next level. It looks like It takes a lot of mathematical discipline. Here, This post buys me to get better at proof writing. So, I think is useful to ...
14 views

### How to split out tax components

I am working on a problem where I want to split out different tax rate components. Example: Income $= \$1,230,903.00$Dividends$= -\$2,456.00$ $1231 -\$5,116.00$Credits$-\$2,161.00$ Long ...
46 views

### Transformation of $\log(X)+\log(1-X)$, where $X$ is uniform.

I am trying to calculate the variance of: $$\log(X)+\log(1-X)$$ where $X \sim \mathrm{Unif}(0,1)$. So far, I have tried to use a random variable transformation, i.e. define $Y=\log(X)+\log(1-X)$, ...
28 views

### Weird behaviour of CLT's application to binomial.

I am carrying out the simulations of the following experiment for all $n$ in the set $\{1,2,3,...,100\}$. (0) Set $k=0$. (1) Generate $n$ $Bernoulli(0.9)$ trials. (2) Construct estimate ...
42 views

### Solving $x^e =c$ in $\mathbb{F}_{p}$

Find all solutions to the equation $x^3=7$ in $\mathbb{F}_{13},\mathbb{F}_{19}$ and $\mathbb{F}_{35}$. In An Introduction to Mathematical Cryptography (Hoffstein et al), we have that proposition ...
60 views

42 views