Month: February 2017

Statistics: estimating population size using order statistics

The tutor demonstrates a way to estimate population size from three serial numbers. Imagine you walk into a room after a convention. The participants had been given, not name tags, but number tags. You find three tags: 21, 225, and

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Math, chemistry: conversion of natural logarithm (ln) to log base 10

The tutor tells a quick hint about calculations with logs. Although base e log (ln) is often used, some lab scientists prefer base 10 log (aka, common log or simply “log”). Typically, of course, logx is assumed to be base

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Physical chemistry: vapor pressure: why a car may be harder to start in the winter

The tutor implicates the Clausius-Clapeyron equation to explain why combustion is more difficult at lower temperatures. To burn, a fuel must evaporate.1 In colder temperatures, fuel has less tendency to evaporate. For two specific temperatures (T1 and T2), the Clausius-Clapeyron

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Dedicated video memory (Adapter RAM): how to see it with OpenGL Extensions Viewer (realtech)

The tutor tells one way to find how much dedicated video memory your system has. This article describes his experience with Windows 7. In my February 19 post I discuss the difference between adapter RAM (aka dedicated RAM, vRAM, discrete

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Geography, Social Studies: ISIS or ISIL?

The tutor explains two names for the Islamic State, commonly called ISIS. ISIS and ISIL are two names for the same group. Both are acronyms: ISIS: Islamic State of Iraq and Syria. ISIL: Islamic State of Iraq and the Levant.

Chemistry: conversion of Hvap from Btu/gal to kJ/mol for gasoline

The tutor converts, for gasoline, the enthalpy of vaporization from Btu/gal to kJ/mol. The density of gasoline is approx. 6.25lb/gal; its heat of vaporization is 900Btu/gal. Its molar mass is approx. 114g/mol. Then the conversion is 900Btu/gal x 1gal/6.25lb x

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Computer systems: graphics memory: adapter RAM vs total memory

The tutor shares ideas about adapter RAM (aka dedicated RAM, vRAM, discrete RAM) vs total. Apparently, adapter RAM is physically dedicated to graphics. In the context of graphics memory, total memory refers to system RAM available for processing graphics. (From

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Chemistry: a textbook correction

The tutor suggests a correction to example 11.2 in Chemistry (sixth edition) by Charles E. Mortimer. Example 11.2 (page 275) of said textbook is about the Clausius-Clapeyron equation. At one point, the equation becomes log(0.526/p1) = 0.491 Then, the antilog

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French: verbs: how to form the imparfait

The tutor shows the easy trick to form the imparfait. Way back in my post from Aug 24, 2012, I mentioned when to use the imparfait vs passé composé vs plus-que-parfait. Today, it’s been brought to my attention that many

Spreadsheets: Excel, LibreOffice Calc: number formatting: how to get rid of E-05 (for example)

The tutor explains how to change from scientific notation to regular number format in Excel or LibreOffice Calc. In my post from Feb 14 I mention that 1.69e-05 equals 0.0000169. Written 1.69e-05, the number is in scientific notation. Perhaps the

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