Question

please solve q 24 with complete correct answer

Answer 1

given:- 
sn=700000 n=7 d=-20000 a=?
sn= n/2[2a+(n-1)d]
700000=7/2[2a+(7-1)-20000]
1400000=14a-840000
14a=2240000
a=160000
so the first prize will be of rs 160000
so second prize = a+d = 160000+(-20000) =rs140000
similarly
third prize of rs 120000
fourth prize of rs 100000
fifth prize of rs 80000
sixth prize of rs 60000
and seventh prize of rs 40000