question 1 :
(17 x 33) / 100 = 5.61
5.61 x 7 +17 = 56.27
After 7 weeks there are nearly 56 worms.
Question 2 :
999 = 5.61x+ 17
999 – 17 = 5.61x
x = 982 / 5.61
x = 175.04
There will be 999 worms after 175 weeks.
Question 3 :
9 x 6 x 6 = 324
After 1 day, birds eat 324 worms.
3 x 324 = 972
If they begin eating at sunday, wednesday they should have eaten 972 worms.
The answers you gave on 1 and 2 are wrong.
1) you have to use this formula: K=K0(1+r)^n (y=b*a^x)
r is persent, and n is the number of weeks.
K=17*(1,33)^7 = 125,144
there will be 125 worms after 7 weeks.
2) We now use the same formula:
999=17*(1.33)^x
x=log(999/17)/log(1,33)
x=14,28
it will take 15 weeks to make 999 worms