Pre-service mathematics teachers' use of probability models in making informal inferences about a chance game

This study considers probability models as tools for both making informal statistical inferences and building stronger conceptual connections between data and chance topics in teaching statistics. In this paper, we aim to explore pre-service mathematics teachers’ use of probability models for a chance game, where the sum of two dice matters in winning the game. We report on an interview with a group of three pre-service teachers as they engaged in predicting and conducting experiments and computer simulations as an attempt to develop a winning strategy. This paper focuses on how the participants came to use the theoretical model of the sum of two dice as they tried to coordinate the combinatorial analysis and the use of data as evidence in their predictions

Investment attractivness and the ways of its improvement

This article contains theoretical and analytical material of such concept as “investment attractiveness”. The definition of “investment attraction” and the technique of its determination in the organization are analyzed. The main directions of improvement of investment attractiveness in the organizations and enterprises were suggested

Small-Size Resonant Photoacoustic Cell of Inclined Geometry for Gas Detection

A photoacoustic cell intended for laser detection of trace gases is represented. The cell is adapted so as to enhance the gas-detection performance and, simultaneously, to reduce the cell size. The cell design provides an efficient cancellation of the window background (a parasite response due to absorption of laser beam in the cell windows) and acoustic isolation from the environment for an acoustic resonance of the cell. The useful photoacoustic response from a detected gas, window background and noise are analyzed in demonstration experiments as functions of the modulation frequency for a prototype cell with the internal volume ~ 0.5 cm^3. The minimal detectable absorption for the prototype is estimated to be ~ 1.2 10^{-8} cm^{-1} W Hz^{-1/2}.Comment: 11 pages, 5 figure