APR of Payday Loan

I watched a video (Figure 2) that shows Rep. Katie Porter (Figure 1) grilling the Director of the Consumer Financial Protection Bureau (CFPB) Kathy Kraninger in regards to the calculation of a payday loan's Annual Percentage Rate (APR). This blog post will show how to compute the APR for the payday loan example Rep. Porter attempts to get Ms. Kraninger to compute. I am not sure Ms. Kraninger knows exactly what APR is. The questioning is a bit uncomfortable because Ms. Kraninger is in no mood for a math exercise and Rep. Porter is not going to give up. Ms. Kraninger clearly is uncomfortable, but her discomfort is nothing compared to the discomfort experienced by a payday loan customer. Continue reading

Posted in Financial | 2 Comments

US Government Management of Western Forest Lands

I am always looking for data analysis exercises for the young folks that I tutor online. While watching the coverage of the massive forest fires on the west coast of the US, I noticed that all the media were reporting that much of the forest land in these states are managed by the US government, which makes them responsible for managing these forests. I thought it would be a good exercise to show the students how to calculate the percentage of forest land that is managed by the US government. Continue reading

Computing Bacteria Reproduction Rate and Doubling Time

Until the arrival of the coronavirus, I looked forward every week to volunteering at a local library as a tutor for university students. Now that COVID is raging around me, I have moved the tutoring online. Most of the students are training for some form of a medical career. This week a student presented me with bacterial growth data and was wondering how to estimate the growth rate and doubling time for the bacteria using Excel. This exercise nicely illustrates the entire data analysis process (Figure 1) in a single example and I decided to post my solution here. Continue reading

Posted in Excel, General Mathematics, Health, optics, Statistics | 2 Comments

I recently have been working on Bluetooth Low Energy (BLE) systems and estimating the distance between two devices based on the Received Signal Strength Indicator (RSSI) value is one of my tasks. There are all sorts of uses for this distance information in wireless systems. Continue reading

Posted in Electronics, Physics | 4 Comments

Gravity on Von Braun Station

I have been reading about Wernher von Braun's work with Disney on popularizing the idea of spaceflight with the public. He was a genius at marketing and a tireless champion for space flight. In addition to his television work, he also gave numerous speeches to any group that would listen. I smile as I think about my high‑school physics teacher beaming with pride when he spoke of von Braun arriving in a helicopter to speak to local physics teachers about space and flying to the moon. My physics teacher could not remember the details of what von Braun spoke about, but his entrance and exit in a helicopter made a huge impression on a town of 1800 people! Continue reading

Posted in Space | 6 Comments

The Amazing de Havilland Mosquito

During the routine demolition of an old de Havilland Aircraft building in 2017, a treasure trove of 20K aperture cards (a microfilmed archive) was uncovered that contained plans for the Mosquito fighter-bomber (Figure 1). These plans have been lost since Mosquito production ended in  1950. Continue reading

USNS Comfort Bed Count Relative To Other US Hospitals

Because of COVID-19, I am currently sheltering-in-place at my cabin in northern Minnesota. I was reading news reports of the USNS Comfort docking in New York City to provide the city with another 1000 bed hospital. I had no idea as to the average size of a hospital and decided to take a quick look at the number of beds in hospitals around the United States using a histogram. Continue reading

Maple Sap is Sweet This Year

I am being a good citizen and am socially distancing at my cabin in northern Minnesota – avoiding people is easy in the dense forests that surround my residence. When I went out for my daily walk and I saw the maple sap bags that my neighbor put out (Figure 1). Most folks around here collect their sap in these blue bags. Continue reading