CHEWY'S SCRIBE POST

Hi everyone! It’s me Chewy, today is my turn to scribe my post. We started class with a usual POD, today’s problem was:

POD 5/14:

In 1990, 2,509 surfboards were made in Brazil. Statistics show that each year the production increases by 659 surfboards. According to statistics how many surfboards have made from 1990 to the end of last year?

As soon as we read the problem we deduce that is an arithmetic series problem.

The question is how can we solve it? First we have to subtract the last year to the first, after doing the math we noticed that 2006-1990= 16, but we have to add 1 because there were surfboards also made in year 1990, so it equals to 17. Then to find the amount of surfboards that were made from 1990 to the end of last year, we have to use a formula, which is: Tn= T1+(n-1)d. Then we plug in T1 which is 2,509 and n which is 17, and d is 659. Then plug in all does numbers in the formula.

Procedure:

Tn= T1+(n-1)d
T17=2,509+(17-1)(659)
T17=2,509+(16)(659)
T17=2,509+10544
T16= 13,053
S17= 17/2(2,509+13,053)
S17=132,277

Then the class continued and we start to practice some arithmetic and geometric series problems with the word problems that 11B did for homework.

Some examples are:

a) A special machine gun shoots 10 bullets per second, but each second its rate doubles. So if in the 1st second it shoots 10 bullets then in the 2nd one it’s going to shoot 20, n the 3rd 40 and so on. Find how many bullets can be shot in 60 seconds.

Immediately we noticed that this is an geometric series problem.

1second= 10 bullets
2second=20 bullets
3seconds=40bullets

We noticed that each second the bullet doubles. So we have to use this formula in order to get the answer. Sn=T1(1-r^n)/(1-r). We know that T1= 10, n=60 and r=2 because each time it doubles.

Procedure:

S60= 10(1-2^60)/9(1-2)
S60= 1.1529215*10^19 bullets.


b) One student fell on the soccer field 2 friends came to see what happened, every minute 2 more students came, than the one’s that came before. In 10 minutes how many students will there be on the soccer field?

This is an Arithmetic Series problem.

In order to solve this problem we have to use the next equation: Tn=T1+(n-1)d.
So T1 is 3 because in minute 1 there are 2 friends that arrive plus the one that is injured, n is 10 because we are looking how many students will there be on the soccer field in 10 minutes and d is 2 because the sequence adds 2 each time.

Procedure:

T10= 3+(10-1)(2)
T10=3+(9)(2)
T10=3+18
T10=21 students.

c) A skater started with a velocity of 4 km/hr, if he doubles his velocity each kilometer what will be his velocity on the 30th kilometer?

This is a Geometric Series problem.

We noticed that in 1km=4km/hr, 2km=8km/hr and 3km=16km/hr. So in order to get the correct answer we should use the next formula: Tn=T1*r^n-1.

Tn= 30 because we are looking for the velocity in 30km.
T1= 4
r=2

Procedure:

T30=4*2^30-1
T30=4*2^29
T30=4*536,870,912
T30=2,147,483,648

THIS IS MY SCRIBE POST, I HOCHPE IT HELP YOU GUYS TO ANSWER ALL YOUR DOUBTS AND QUESTIONS.

cheeewwwyyy...

***I choose chippy and jose to do the next scribe.***