Because of how long it takes to form underground and then it moves to the surface and cools rapidly
One of the influences of the Arabs when they came to Africa was trade.
When the Arabs came to Africa, they traded heavily with the Swahili people and shared the Islamic religion with them.
<h3>Africa and the spread of Islam</h3>
Around the eighth and ninth centuries, there was am influx of Arabs especially in eastern Africa.
Arab traders and travelers, began to spread the religion along the eastern coast of Africa especially to the swahili community in Eastern Africa.
Other people to which Africans traded with around the same period were Persians, the Indians, the Chinese etc and this trade was referred to as the Indian Ocean trade.
Learn more about the Indian Ocean trade at brainly.com/question/24686699
Answer:
mean of all 30 students is 69
Explanation:
given data
students = 30
mean = 29
μ = 68 points
student scored = 98 points
to find out
What is the mean for the class of all 30 students
solution
we know here mean score of 29 students is 68
so sum of score is here = 29 × 68
sum of score = 1972
so
sum of 30 students score is = sum of 29 students score + missing score
sum of 30 students score is = 1972 + 98
sum of 30 students score is = 2070
so
mean of all 30 students is = 
mean of all 30 students is = 
mean of all 30 students is 69
