Answer:
Step-by-step explanation:
The nth term of a geometric sequence is expressed as Un = ar^n-1
a is the first term
r is the common ratio
n is the number of terms
U5 = ar^5-1 = 40
ar^4 = 40 ......... 1
Also U10 = ar^9 = 303.75 ....... 2
Divide equation 2 by 1
ar^9/ar^4 = 303.75/40
r^5 = 7.59375
r = 1.5
substitute r = 1.5 into equation 1
ar^4 = 40
a(1.5)^4 = 40
a(5.0625) = 40
a = 40/5.0625
a = 7.9
u15 = ar^14
u15 = 7.9(1.5)^14
u15 = 291.93 * 7.9
u15 = 2306.24
