Answer:
BEC = C. 50
BCD = A. 120
Step-by-step explanation:
BEC
65 + 65 = 130
180 - 130 = 50
BCD = 180 - 60 = 120
BEC is 50
Answer:
78
Step-by-step explanation:
Given that:
First day (a) = 1
1 more pebble every subsequent day than the previous day
Tn = a + (n - 1)d
d = common difference ; difference between pebbles in two successive days = 1
n = nth day
At the end of the 12th day;
Tn = a + (n - 1)d
T(12) = 1 + (12 - 1) 1
T(12) = 1 + 11
T(12) = 12
Appling the sun if arithmetic progression formula : Sum of AP:
n/2 (a + Tn)
n = number of terms
12/2 (1 + 12)
6(13)
= 78
90 < [( n + n + 2 + n + 4) / 2] < 105
90 < (3n + 6) / 2 < 105
3n + 6 > 180 and 3n + 6 < 210
n > 58 , n < 68
58 < n < 68 answer
The first option is the correct choice of answers.
