21. The mean age of 15 pupils in a class is 14.2 years. One new pupil joined the class and the mean changed to 14.1 years. Calculate the age of the new pupil.
A. 12.4 years
B. 12.6 years
C. 13.2 years
D. 14. 1 years
22. The distance 3 metres of a particle from a fuel point at time 1 seconds is given by s = 7 + pt3 + t2, where p is a constant if the acceleration at t = 3 seconds -s 8ms-2, find the value of p
A. 1/3
B. 4/9
C. 5/9
D.1
23. The probabilities that a husband and wife will be alive in 15 years time are m and n respectively. Find the probability that only one of them will be alive at that time.
A. mn
B. m + n
C. m + n - 2mn
D. 1 - mn
24. In a class of 50 pupils, 35 like Science and 30 like History. What is the probability of selecting a pupil who likes both Science and History?
A. 0.10
B. 0.30
C. 0.60
D. 0.70
25. P, Q, R, S are points in a plane such that PQ = 8i - 5j, QR = 5i + 7j, RS = 7i + 3j and PS = x i + y j. Find (x, y)-
A. (-6,-15)
B. (-6, 5)
C. (20, 5)
D. (20,15)