The summer income of the 3,408 students at Van Buren High School last year was normally distributed with mean $1,751 and standard deviation $421. a. Approximately what percent of the students had incomes between $1,000 and $2,000? Round to the nearest percent.

b. Approximately how many students had incomes less than $800? Round to the nearest integer.

Asmall (but heavy) particle placed in a glass of water will follow a zigzag motion because the particle will bounce off of the water molecules it meets. this is called brownian motion. a physicist simulates this on a computer, by varying the distance a particle can travel (called the mean free length), on average, before it collides with a water molecule and assigning the change in motion to be one of 8 directions, each with a similar probability. by running the simulated particle (with the same mean free length) many times she determines that it should take 15 seconds, on average, for the particle to fall to the bottom, with a standard deviation of 1.5 seconds. next she lets a real particle fall through a glass of water and finds that it took 18 seconds. what does she conclude, and why?

Ineed to know how to write question one in mathematical terms

Amotorboat maintained a constant speed of 12 miles per hour relative to the water in going 45 miles upstream and then returning. the total time for the trip was 8.0 hours. use this information to find the speed of the current.