Math Word Problems: Set 1

If log27 = 1.431, then the value of log 9 is

0.954. 27 is equal to 3^3, use power rule, 1.431 / 3 = .477 = log3. Then 2 * log3 (9 is 3^2) to obtain .954.

The present worth of Rs. 1404 due in two equal half-yearly installments at 8% per annum simple interest is:

Rs is rupees I guess? 1325. Split into 2 half, so 702 each period. 8% per annum, so 4% then 8%. 675 + 650 = 1325.

The banker's gain on a sum due 3 years hence at 12% per annum is Rs. 270. The banker's discount is:

1020. Banker's Discount!

What is the difference between the compound interests on Rs. 5000 for 1 1/2 years at 4% per annum compounded yearly and half-yearly?

2.04 RS. When compounded yearly vs compounded half-yearly! Amount = P [1 + (Interest in decimal/nbr of times it compounds per year) ]^ years * nbr compounded per year

A sum fetched a total simple interest of Rs. 4016.25 at the rate of 9 p.c.p.a. in 5 years. What is the sum?

Simple interest! Total Interest = Principal x Rate x Time Total amount = interest + principal 8925. 4016.25 / (.09 * 5)

If 3√5 + √125 = 17.88, then what will be the value of√ 80 + 6√5 ?

D, 22.35. Simplify!

The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero?

19. You can have a bunch of positive numbers then one big negative, then divide by 20. As long as the large negative can cancel out the positives.

In a class, there are 15 boys and 10 girls. There students are selected at random. The probability that 1 girls and 2 boys are selected is:

21/46. Probability. Number ways to select 3 students is (25 * 24 * 23)/(3 * 2 * 1) = 2300. Number ways to select 1 girl and 2 boys is 10 * (15 * 14) / (2 * 1) = 1050. 1050 / 2300 = 21 / 46.

In a 100 m race, A can beat B by 25m and B can C by 4 m. In the same race, A can beat C by:

A:B = 100:75, B:C is 100:96, to get A:C you need to multiply each together. You get 100:72, 100 - 72 = 28.

A man standing at a point P is watching the top of a tower, which makes an angle of elevation of 30º with the man's eye. The man walks some distance towards the tower to watch its top and the angle of the elevation becomes 60º. What is the distance between the base of the tower and the point P?

Data inadequate

Excluding stoppages, the speed of a bus is 54 kmph and including stoppages, it is 45 kmph. For how many minutes does the bus stop per hour?

When the bus is stopped, kmph is 0. 45 kmph(60) = 2700. 54(a) + 0b = 2700. a + b = 60. Using these two formulas, you can get the answer. 2700 / 54 = 50, meaning 50 mins moving and 10 mins stopped.