1. what is the diode?

diode is a two terminal device. It allows current to flow only in one direction.

2. Oshkosh did a study of the colors used in African national flags. He found that 38 flags have red, 20 have blue, 13 have both red and blue, and 8 have neither red nor blue. How
many flags

a. have red but not blue?
b. have blue but not red?
c. were included in the study?

n(r)=38
n(b)=20
n(r & b) = 13
n(r+b) = n(r)+n(b)-n(r&b)
= 38+20-13
= 45 (flags with either red or blue)
total flags(study) = 45 + 8(neither red nor blue) = 53

red not blue = 38-13 = 25
blue not red = 20-13 = 7

7. Find the least number which when divided by 7 gives the reminder 6, when divided by 6 gives reminder 5, when divided by 5 gives reminder 4 and so on?

Try trial and error method for the multiple numbers of 7
you will get a number 119 which should get a remainder 6 when divided by 7,5 when divided by 6,4 when divided by 5,3 when divided by 4,2 when divided by 3,1 when divided by 2,

8. If a man stands in front of sun what is the first letter of the direction which is left to him?

its a kind of trick question ....as sun can be considered as
a sphere of burning gases and not a circle...so it can be
any direction on the left of person standing in front of the
sun.