Without the use of a calculator, solve maths questions

Ahm97sic SG

There is an interesting discussion in the thread poisson distribution that discusses the use or without the use of a calculator to solve maths questions.

Do you/we know how to find the answers to the following questions without the use of a calculator or a mathematical table ?

(1) Calculate the value of square root of 19 or cube root of 86 ?

(2) Calculate the value of sin 56.3, tan 87.2 ?

(3) Calculate the value of x if sinx = 0.48 ?

(4) Calculate the value ln 2.3 ?

(5) Calculate the value of 2^1.2 ?

(6) Calculate the value of r if the equation is

150 - 150r = r - r^20

(7) Sketch the curve y = (2x + 3)/(3 - 5x) + 3

(8) Calculate the probability value of P(0.32 < Z < 0.73), where Z is a standard

normal variable ?

Thank you for your kind attention.

Regards,

ahm97sic

skythewood SG

1) square root of 19 is between 4 and 5. so try 4.5, manually do is 20.25. than adjust the answer and try again. i call this brute force

4) looks like a number. solve what?

7) find x and y intercept and, looks like a maximum curve

the rest i don't know. even the one i answered i don't know if is correct

maurizio13 SG

Ahm97sic don't seem to be a student. A tuition teacher giving questions to students for practise?

skythewood SG

that doesn't look like stuff kids who need tuition will be doing

jayh272416 SG

1) plot graph of y=19-x^2, then see the intersection point.

caleb_chiang SG

if never math table, who on hell would remind the value of sin, cos and tan?

Ahm97sic SG

Hi everyone,

There is a discussion in the thread poisson distribution that discusses whether there is a need to know how the calculator gives us the answer ie

when we press square root 2, the calculator gives us an answer of 1.414, it can be calculated manually using a method called long division algorithm as explained in the Wikipaedia.

The objective of starting this thread is to let students to think more and not just rely only on the calculator especially when students do not know how the calculator gives them the answer eg why sin 56.3 is 0.83 ? why tan 73.2 is 3.31 ? Why ln 2.3 is 0.833 ? Why 2^1.2 is 2.297 ?

Thank you for your kind attention.

Regards,

ahm97sic

skythewood SG

1) plot graph of y=19-x^2, then see the intersection point.

nice... interception with y-axis....

for sin x, use the taylor series expansion... just very the tedious

http://www.ucl.ac.uk/Mathematics/geomath/level2/series/ser121.html

jay_rocks SG

Tt's why calculator is our best fren, decreases time needed to calculate without using tedious mtd